I just posted a step-by-step assembly of super easy DIY LED, which I have done about a year ago. 1 year is a long time in the progress of LED technology, but Philips XF-3535L is still great in terms of efficiency. The price came down a little bit over the year, but COB (chip-on-board) LEDs (such as Cree CXB series and Bridgelux Vero) are still cheaper. But there are lots of positives about XF-3535L.
I mostly use it for orchids, but it can achieve fairly high light for CP if you use lots of them. So it may be useful for some of you.
Here is the link to the blog post:
Orchid Borealis: Easy DIY LED: Philips XF-3535L