"This would not be lucrative in my opinion".
Yep, not very considering the time required, however it does pay almost equal with Micky "D"s, plus it's enjoyable.
A couple years ago a fellow had a HW55 piston that had been modified to use a "donut style" seal and he wanted to revert back to a factory seal. He sought "high and low" for a replacement piston everywhere from Beeman to HW in Germany and the piston simply wasn't available at any price. Well.....I reconstructed his piston and it was a different design than the one in the original post. Matter of fact, I've oring sealed a couple HW55s and their pistons were of a different type. Here's a couple pics of the piston after reconstruction.......
As you can see it's design is like a small R9 piston.
Since taking on this latest project I've learned that I must be working on a piston from an older HW55 and the "double slotted" was common.
I have built/modified quite a few pistons up to now and here are a few pics..........
Lower FWB124 piston was a special light weight version built completely from scratch, including the latch rod....these weren't cheap!
Lightened and buttoned factory R1 piston with added oring sealed piston cap.
Home fabricated R9 piston with experimental molly filled nylon oring sealed piston cap. I've since nixed the molly filled nylon piston cap and reverted back to aluminum alloy.
Anywhoo.......I've made a few chips and SCRAP in my years of airgun mods!