Hey guys a lot of you know me from RIU or ICMag but for the LED growers here that have not seen it, here is the recipe for building DIY LED very cheaply. Why build a DIY lamp? You can get up to 49% efficiency if you can find the top bins and run them soft (700mA). You can get 36% efficiency with the mid bin running hard (1400mA). The best commercial LEDs (Area 51, Apache, Onyx) are in the low 30s. Another advantage is the ability to have remote drivers to keep that heat out of your grow space and away from the LED heatsinks.Everything has changed since COBs became available to us. It is much easier to build a lamp and it turns out that 3000K works just fine on its own, better than HPS even.For the simplest build the best COBS to use are the Cree CXA3070 and Vero 29. The CXA 3000K has 14% blue and the Vero 3000K 8-10%. They are available on Digikey or if you need a bulk order you can save $ on Arrow.As far as drivers go, 1.4A is a good compromise between cost and efficiency. They are available on eBay for $13 , 90% efficient and power factor corrected. You can use Mean Well LPC-60-1400 but it is lower efficiency and not power factor corrected. If you want to run at 1050mA you can use Mean Well LPC-60-1050. The one I tested was 88% efficient.For heatsinks, CPU coolers work great for small grows. The 92mm Arctic 11 Plus is a favorite because it can be found for $10 and uses a fluid dynamic bearing fan, lots of cooling power and not too loud. Amazon and Newegg sometimes offer them for $10. Currently outletPC has them for $10 with reasonable shipping cost.If you are building a medium or large lamp, I recommend HeatsinkUSA 5.88" profile . A 12" length is good for (2) COBs and a 24" length is good for (4) COBs. You can cool it with a single 140mm fan to make a super efficient cooling combo. I recommend the Prolimatech 140mm $11 from Amazon . It is quiet even at 13V and moves a lot of air.The Vero is solder free but the Cree requires a COB holder and to go solder free. Both methods require drilling and tapping the heatsink. I don't mind the soldering so rather than drilling, I mount the COB with Prolimatech PK3 thermal paste and then use kapton to tape the COB in place so it cannot slide sideways. The paste makes a very strong vacuum when you press the COB onto the heatsink. It will not come off from gravity or heat. If you try to pry it off it will break. You have to twist it and then slide it sideways to get it off.Small build:Medium build:Large build: