Plastic parts are good for communal bathing. Fun to slosh bag, no breaking.
Iso in baggie, warmed by a very hot water bath . Effective and quick with agitation.
This is a well known tip, but thought new readers may be interested.
I'm far too lazy to follow the S&B official CU cleaning method, and too lazy to reclaim. Separate CUs, toss them in the bag, don't bother removing o-ring seals.
Kinda funny, the hardest part is separating the CUs. Especially a bunch sitting for a while, getting all glued together with resin. Here's my cheat: Put them in baggie, add very hot water, wait until you can comfortably reach in and separate while warm. Your fingers will get sticky if you don't wear gloves.
Edit: Very dirty CUs will require some scraping in corners
Iso fumes are dangerous. No flames or sparks allowed. Frightens me when I read posts about nuking iso in a microwave -- insanity!