What your looking at here was the first thing we worked on, Peter KA1QEK found some copper and aluminum heat sink. He had a machinist friend work it out so they were connected pretty flat. Lots of hardware on top and underneath to hold it together, our concern was dissipating 1kw off this thing. The fan would be moving air thru the bottom, I’ll post a picture later to show you the openings underneath it. I was still undecided at this point how I would mount it in my case i had gotten many years ago just for this project! I knew someday it would come in handy! Yea I tend to hold onto things! the FETS are the 250w SD2933’s, we got them as pulls. You do need to test them first as some can get damaged, but all mine were fine.
this works but instead of your finger, for these you will need to put the positive lead on it as you’ll need a higher voltage.
Believe me, this has been going on a year we will get into it later on how I know this , I cooked the first set last week (~52 weeks into this haha)