I used Linux, I found a half-working script somewhere on the MiSTer projects, then found a slightly improved version in some random GitHub fork, and used that after fixing some syntax errors (!) in the bash script. I see there's a recent script in the Linux_Image_creator_MiSTer project which is probably better, there's a similar script for macOS linked from the wiki. If anyone needs help getting it working on a Linux system I'm happy to help. I dremelled up an old southbridge heatsink to fit the top of the FPGA SoC, I also didn't have any thermal epoxy but it's about half a millimetre too tall, so I used regular thermal paste and screwed down the perspex top plate over the top of the heatsink - it holds it down with adequate pressure Shouldn't need a fan in an open-style case I think.