My big problem with making custom parts for other folks is that I like to take my time and I couldn't possibly charge an hourly rate accordingly, Tone.
The Pistons I've shown that I've made have all been for my own guns, so I never take the cost into consideration with them.
I'd rather leave the custom parts making to other folks rather than get too involved in things so I would also recommend NickG for this.
All the best Mick