Piston Pin tool?

Greetings,

Aside from the official Rotax tool, has anyone used an off-the-shelf piston pin tool for removal and installation of 921 piston pins?  Without having the pistons in front of me, it's hard to tell what size it needs to be.  I know the pins are about 3/4" (20mm), but I'm not sure about the shape of the piston around the pin. 

Thanks,

Rusty