Nah don't bother with the tool just as easy to do it with your fingers, its not hard at all

Best way I have found to clean pistons, soak it in petrol for as long as you can afford to.
For carbon in the grooves, get one of the old rings, break it, and use this to get into the grooves.
To do the top of the pistons, use a thick plastic scrapper or (very carefully) a metal scrapper.

If you are putting the rings onto the piston, slap lots of oil onto the piston and rings, the rings will go on by hand.

When you are putting them into the block, go spend $30-50 on a ring compressor from Repco or alike.

When utting the rings in, its easier to start with the oil ring and work your way back to the top from there. Just make sure you dont let a ring slip into the ring gap of another ring as theyre harder to get out

As for a ring compressor, it makes it much easier, and stops you slipping with anything like a screwdriver. But if youre cheap, be careful, and you should be fine with either fingers or a screwdriver wrapped in an oily rag. that way, if youdo slip, it wont score the side of the piston.

sweet! might be safe and buy a ring compressor!
is that ea citric acid?? im wanting to paint mine citric acid, but im still undecisive!