i've found a used HPS/MH( comes with both bulbs) lamp with the ballast but not the reflective hood for a cheap price on ebay.
so the questions i have are..
1) what order will i use the lights? ( by this i mean like HPS for veg MH for flower ect )
2) will i be able to make a hood easily or are they cheap ?
1. How inexpensive is the used Ebay light and is the ballast magnetic or digital? You said MH/HPS but you did not say if that was due to a switchable ballast or just using a MH conversion bulb.
2. As was mentioned the Metal Halide bulb would be used for the vegetative growth stage and the High Pressure Sodium would be used for flowering growth stage. That is in part where it is important if the used system will burn a true MH or a MH conversion bulb. For veg you want blue light, something in the general range of 6500 Kelvin. Normally MH conversion bulbs are not found in that Kelvin range and often are not really all that different from the Kelvin range of an HPS bulb. Basically they are broad spectrum bulbs with an ever so slightly increased blue spectrum. It is sort of a tricky way to sell light systems. Advertise them as able to use both MH and HPS bulbs but don’t bother to mention what type of bulb the MH will be and just allow the buyer to believe they will be receiving a system/bulb that is a true quality MH bulb suitable for vegging and then just let them sooner or later figure out they ended up with a broad spectrum Kelvin range bulb with just a tiny bit more blue in it than a standard HPS bulb.
3. The answer to your question of will you be able to manufacture a reflective light hood easily enough, and I assume you would also care to know if it will be of adequate quality. The answer to that would depend on the quality of the materials you could afford to purchase the accessibility, or lack there of to certain types of tools and equipment and of course your level of skills of manufacturing.
Unless you know someone with a quality hood that you could measure and use for your layout/blueprint I hate to sound insulting but likely at best you might be capable of being able to match the very lowest grade of reflective hood that you could purchase. Even with the needed equipment and tools and skills and using quality materials lacking a quality template/model to duplicate, and I do mean duplicate, you will not end up with equal even light distribution. If you were only using CFL's’I would say it is not that big of a difference because as weak as they are hotspots are not a major concern. But if you are burning 400 watts and your reflective hood is not reflecting it evenly and equally you can easily fry areas of plants due to hotspots.
Any quality reflective hood is made of dimpled aluminum that has a coating on it to keep it from tarnishing and retaining its reflective capability. Material like that is not the cheapest of aluminum. By the time you purchased it and unless you are the kind of person who can go out into the wild with a bent screwdriver and a Q-Tip and build a mall, well you just aren’t going to end up with a homemade reflective hood worth the money and time you have spent on it.
As I mentioned I do not know what you consider to be inexpensive for a used 400-watt MH/HPS grow light but for example you can purchase:
Digital Greenhouse Ultimate 400 watt HPS & MH Grow Light
System includes:
* 400 watt Digital, Electronic Remote Ballast
* Lightwing Horizontal Reflector
* 400 watt HPS High Output Horticultural bulb
* 400 watt GrowBright Metal Halide (MH) bulb
* Socket / Cord Set
About the system:
This 400 watt system is recommended for gardens anywhere between 3’ x 3’ (floor space) to 5’ x 5’.
BOTH A METAL HALIDE & HIGH PRESSURE SODIUM Grow Light system in one!
Growers worldwide consider the best way to grow flowering plants is by vegetatively growing them under the bright white light of the METAL HALIDE then switching over the the High Pressure Sodium’s super bright orangish/red spectrum for the flowering stage of plant growth. The Metal Halide bulb provides lush, compact plant growth. The HPS bulb’s spectrum mimics that of the "harvest sun" and promotes explosive, prolific flowering of plants.
Using Metal Halide and then switching to High Pressure Sodium is THE way to GROW the BEST PLANTS POSSIBLE.
This is simply the BEST High Intensity Discharge (H.I.D.) Grow Light System on the market today. Top Qualtiy Construction and Components combined with Outstanding Value make this the perfect choice for your grow light needs.
DIGITAL BALLAST info:
DIGITAL TECHNOLOGY IS THE GREATEST ADVANCEMENT IN GROW LIGHTS IN 35 YEARS!
MANUFACTURED BY "DIGITAL GREENHOUSE"
The DIGITAL GREENHOUSE Electronic ballasts are more efficient and reduce energy consumption. The DIGITAL GREENHOUSE Electronic ballast improves lighting quality and increases garden yields.
The DIGITAL GREENHOUSE ballast features patented "soft-start" technology which increases lamp life and stops voltage spikes on your power meter. The soft-start technology allows for 50% less power consumption during lamp startup.
The DIGITAL GREENHOUSE electronic ballast is lighter, smaller and more reliable than standard technology "core and coil" ballasts. It is also virtually silent, no noise or hum.! The ballast is totally sealed, which protects the unit from dust and dirt, ensuring a lifetime of trouble-free operation.
The DIGITAL GREENHOUSE electronic ballast operates at a high frequency (20,000Hz) instead of the lowly 60Hz of standard core&coil ballasts. This allows the lamp to operate more efficiently, produce more usable light for plants and last longer. Lamp lumen loss is minimized allowing for a brighter system over time and extending usable lamp life.
Energy consumption is reduced and on average will save over $60 per year on electric bills.
The DIGITAL GREENHOUSE electronic ballast operates cooler than standard systems improving ballast life and reducing temperature in your growing area.
The DIGITAL GREENHOUSE electronic ballast will automatically adjust to any input voltage from 90 volts up to 260 volts. It comes equipped with a 10’ grounded power cord, and plugs into standard 120v household current. You can easily change voltage to 220 or 240 volts if you wish.
Digital Greenhouse ballasts are now UL listed! What does this mean? This means that Digital Greenhouse ballasts are now certified for safety by Underwriter Laboratories, the worlds leading electrical product safety organization. Check the other brands, are they listed, probably not. Demand safety, demand Digital Greenhouse.
Digital Greenhouse ballasts now come standard with a 5 year warranty, 3 years complete, 2 years pro-rated!
MaxWing Reflector:
Measures: 19" long x 16 1/2" wide x 6" deep.
The MaxWing Reflector is LARGE and in CHARGE! This 4-sided reflector is made from highly reflective (95%+ reflective) polished aluminum this reflector will not rust, corrode, chip or discolor. NOT made from inferior chrome which, under the intense heat of an H.I.D. lamp, will chip, fade and discolor over time. The MaxWing Reflector is built to last a lifetime. It combines the high reflectivity of the mirror like finish of the polished aluminum with the excellent light dispersal qualities of a dimpled or hammer-toned surface. This is simply the BEST material to use for H.I.D. lighting reflectors. The horizontal configuration delivers the maximum amount of light over the entire garden. Hammer-toned surface eliminates "hotspots" and ensures lush, even plant growth.
LAMPS / BULBS INCLUDED:
400w HPS High Output Horticultural Bulb
This is not your ordinary 400 watt High Pressure Sodium bulb. This is a specialty 400 watt High Output Horticultural HPS bulb made specifically for growing plants. This bulb is head and shoulders above all other 400w HPS bulbs on the market today.
55,000 lumens !!! 10% more light than standard HPS bulbs
30% additional "BLUE" spectrum combined with high "RED" spectrum creates the correct balance for MAXIMUM PLANT GROWTH.
Higher Lumen output for HIGHER YIELDS.
24,000 hour expected life span (one year is 8,760 hours)
ONE YEAR WARRANTY on bulb
400 watt Metal Halide Bulb
The perfect bulb for VEGETATIVE PLANT GROWTH
Make your 400w HPS system into a "switchable" HPS/MH system with this light bulb!
This is a premium high output Metal Halide bulb. This 400 watt High Output MH bulb emits 38,000 lumens - standard 400w MH bulbs which emit only 36,000 lumens. This bulb gives you a higher light output which equates into faster / more plant growth and ultimately higher plant yields.
ONE YEAR WARRANTY bulb
PLUG / CORD SET
The Plug Cord Set features a 15’ heavy duty 16 gauge cord that attaches to the reflector. It’s universal design means it fits many major brand reflectors. This is important if you ever decide to choose a different reflector configuration, including an air cooled reflector.
You have a choice of 9 different reflective hoods in case you wanted to upgrade or just wanted or needed something very different than the standard reflective hood. Upgrade prices run from around $35.00 to $60.00. You can upgrade light bulbs, not something not worth considering but then for the small additional gain for the large increase in price for some bulbs you do not want to instantly jump on any or all upgraded bulbs and assume it was worth the cost.
There are various other options available from light hangers/raisers to different kinds of timers with different numbers of outlets to plug in and some are mechanical and some are digital.
Of course almost any system could be tweaked and upgraded a bit but even the standard system is a good system. Digital Greenhouse is not the Mercedes Benz of digital ballast manufacturers but then it is not the KIA of digital ballasts either. I purchased such a system, with a couple minor upgrades. I went with the less expensive Digital Greenhouse over the Lumatek purely because at the time I believed it would be a fairly short-term, interim light choice and a higher wattage system would replace it well before any lesser quality that might exist in it would ever show up and cause me problem. The expected changes never occurred and to date the system has run flawlessly and while I would never attempt to argue that it is the very best I would readily argue that is most purchasers of the same system received as good or better service out of their light systems as mine then if nothing else the system is a very good value for the dollar.
By the way the dollar figure for the basic system, meaning without any upgrades, is $229.95. The HPS model costs $184.95 and a MH conversion bulb could always be used with it so if the used system relies on a MH conversion bulb it would not be like stepping down if you chose another system that relied on a MH conversion bulb rather than a true MH bulb.
Consider the price of the used 400-watt system you asked about, find out if it is a switchable digital ballast or a magnetic ballast and if the type of MH bulb it uses is a true MH bulb or a conversion bulb and then consider the price of the needed materials, all the needed materials to fabricate a reflective hood yourself and be honest with yourself about your ability to manufacture something that would be at least close to even a lower grade professionally manufactured reflective hood, and of course factor in a bit for your time and then ask yourself which is the better value and go with it, that is unless regardless of value the light system I mentioned is cost prohibitive.
When it comes to the creation of a setup/growing system most mistakes I have seen over the decades have been in lighting. People overestimating the abilities of certain wattage HID lighting just because it is HID lighting. Feeling sure they can spread out a light’s footprint enough to fit the number of plants they want to grow into it when they really need one or even two wattage increases in light to do the job. Someone attempting to save bucks and purchasing bits and bobs here and then and piecing them together and then attempting to manufacture the rest themselves. Not accurately taking into consideration heat issues that will arise in their situation, etc., etc., etc.
Unless you are a real Handy Andy and have access to metal fabricating equipment and know how to weld very well or know someone who can and will and unless you have a high quality light hood to measure and duplicate, and of course use the highest quality materials to do so … well the odds are that in the end if you save money it will not be nearly worth enough to make up for the ghetto-fabulous light you will end up with … and then after a few grows and you finally admit to yourself that you made an error you can just add the cost of your Frankenstein’s monster of a light to the cost of the quality light you replace it with and just figure that is what the quality replacement light actually cost you.
can you buy the hoods on their own ? 
