na mate
remove the circlips with needle nose pliers (you MUST replace them with new ones)
then use a deep fit 16 or 18mm socket, thread some all thread through it with a washer and nut on the back, and on the other side use a 6-8mm deep fit socket backed by a washer and a nut. warm the piston with a hair dryer or heat gun, then use the nuts to push the piston pin into the deep socket. You don't need to push it all the way, just enough so that its clear of the little end bearing.
you can buy a tool for hundreds or use this - if you need force youre doing it wrong
if you heat the piston enough often you can just gently push the piston pin out of the piston ... never tap it out!