Not very current these days, but having wrestled a very reluctant square taper shimano bottom bracket (plastic cups) from an alu frame a few weeks back, a BB tool that had a bolt that screwed into the crank bolt hole to hold the tool tight in the plastic keyways while you could put a big spanner/socket over the end… that would have saved a lot of slippage, broken plastic and swearing.
Of course, now that I’ve typed that out I’ve realised that I probably have a suitable bolt/washer combination in the shed that would have fitted through the 3/8″ drive opening to hold the tool in place, then used a big spanner/socket to take it off.
So a tool that gives you the benefit of hindsight once you have had time away from the problem, but while you are busy making a pigs ear of the job, that would be cool.