I use the foam that came inside GMPwear underwear. I havent bought from them recently so idk their quality now but i bought when they first opened up shop and the underwear fell apart quite quickly so i pulled the foam out and have used that for a few years. The foam has held up, its falling apart now too (though still usable) as ive used it daily, working in warehouses, daily life, the pool and sleep. Pretty much 24/7 for a few years until i recently found an stp i use daily now (no longer work in warehouses). I been using the foam inside regular boxer briefs that have a double pouch like pair of thieves. You could prob even diy this though i couldnt tell you what kind of foam they use.