Thanks
This should do it:
View attachment 4234107
About 11mm wide, i could cut/grind to 8, maybe find 5-6mm version.
What about surface? Should i spray paint it with something, wrap in foil, something else?
Yepp, that would work good. The surface structure does'nt matter much as long as its a metallic surface.
A hammered sheet or a stucco reflector surface would be more diffuse vs. a polished surface but that would not make a big difference at 18-24".
To reflect UVB you are forced to use alu or iron sheets because colors, paints, plastics, glas and all that swallows UVB almost completely. Pretty sure there are UV reflective coatings available but for sure expensive and they would work just the same like any metallic surface. You could polish reflector and spreader surface to optimize UV reflection; thats already enough.
I cut the spreader to fit exactly from the first to the second T5 socket/holder. Then I have made 2 about 10mm deep incisions on each end and bent the middle piece straight flat. I hot glued the magnets to these little flat areas.
I also glued small alu angles to the T5 sockets. The spreader holders has to leave at least a 12mm gap between holder and T5 socket in order to be able to change the bulbs without removing the glued holders. But the best would be you use angle irons from the beginning which are already magnetic. This way there is no need to glue another magnet or iron piece on the holder angles.
Unfortunately I had no angle irons at home so I took aluminum and glued on little iron plates.
At some future point I'm going to replace them through angles made of iron.