If you have the piston and pins piece, all you need is to make a unit to hold that piece. Simple concept, you can make the measurements.
Base disk big enough to support a chunk of double-sided tape that will hold the unit when it gets slammed by the tonearm in the lead out groove, say 20mm diameter. Vertical rod, 7mm diameter x 20mm lenght, attached perpendicularly to this base which is tall enough to allow mounting of the tonearm lift at tonearm lift height (vaires by TT) and big enough in diameter to allow you to drill a hole in it to hold the piston (measure your piston) and another hole, which is tapped, to allow some kind of set screw.
The AT unit has the hole for the piston off center, using a larger diameter rod will make this unnecessary as the one on the AT is that way to give the set screw (a thumb screw in this case) some metal for the threads.
The length of the rod is dependent on the TT. The AT unit has a short one that is only a bit longer than the piston section that will go into it, but they supply a 3/8ths" thick disk the diameter of the mounting disk to use to raise the unit higher if needed.
The set screw is close to the top of the drilled rod so that there is vertical adjustment of the piston and still enough piston in the rod for the set screw to grab it and hold it.
Really very simple to draw out and design yourself.
1) flat disk to mount to table
2) rod to mount perpendicular on the disk
3) rod drilled the diameter of the piston
4) rod drilled on one end to install set screw for piston
5) tap threads in the set screw location based on your set screw choice
6) set up the unit on the tt and see what length you need to mount the AT properly
7) cut the rod to correct length (end opposite the set screw)
8) attach rod to base
9) install piston to rod
10) determine location on TT for the unit. (this may affect base diameter and probably why the AT one is only 20mm)
11) read instruction manual I posted for the AT unit to set up
12) check operation
13) enjoy not having to jump every time a record ends.