Yes i'm surprised no one has brought a proper solution to market, perhaps just no the need, the home made ones are ok, but there are variants on whats required and lengths too, like my BSA mercury's requireda different fitting to the HW's etc, so its not that easy I guess.
I tend not to use them as a whole also, occasionally for decompressing etc. but thats about it. I use an old gym mat, some high density form about 5 inches deep, with a circular cut out to hold the chamber and a square foam block underneath for the breach, so that it can turn on the base mat. Two people are needed, one to hold and turn the chamber and one to compress the spring and hold the trigger block still.
Ive compressed HW80's and Exports, FWB (easy) and Mercury's no problem with this method, few bits of foam, a mat and a mate, thats it, some you can do yourself, as there does not need a lot of preload for most guns to work within 12ft/lbs if tuned correctly, but its always handy having a helping hand to protect that lovely blueing etc.
Good luck, but I've never come across a commercially viable solution, but I'm happy to be advised otherwise.