What is this and where do I get one?

Remove the right hand crank and bottom bracket cup.

Find a vice, hold the RHS of the bottom bracket shell onto the slightly open jaws of the vice.

Next, find a large punch and a large hammer.

Finally, hammer through the BB axle - should come off in 2 or 3 blows.

JOB DONE.

actually that is the best way... Thanks!
I know now how to remove stuck crank arms without damaging them.