I have not opened a Mac mini in a long time so I don't know how much room I have extra inside. That's why I looked at the OWC drive first. I found a lot of adapters but I don't know if it all fit inside the mini.
I found on eBay some 32GB 40-pin IDE Flash Drives for under $10 each shipped. I may buy one and try it.
Macmini G4-1.42, 512MB RAM, MorphOS3.9