Your challenge is to make a really good adjustable two pronged tension wrench
Dunno how easy that is, homebrew... can probably be done...
Look up well known pick suppliers like majestic and LAB etc. and check out what they supply... some of it is pretty cool...
Experiment with different ways of making the wrench stay in the keyway (altering thickness, adding teeth etc)
the main problem I have with using a sweeper bristle wrench is that mine slips in deadbolt lock keyways...
I'd start queueing up for some as well, except for postage... I found all of 2 bristles in my life and now the sweepers in my area seem to have big yellow plastic ones, so I'm going to need to experiment with hot bending myself some hacksaw blade wrenches (which I'd prefer not to have to do)
Ah, well... sweet find man, and good luck with getting a deal going... if nothing else they can et least tell you where they dump all the bristles if they're just trash.
All your locks are belong to us.