Can snap be made or changed yourself ?

[Roland Melkert]

Can give an example:
Part 54200 has no snap, but 54200pc1 does, there are several parts I would like to be able to change, but don't want to start anything until I hear your opinion

Assuming you are talking about LDCad (based on your posting history), I added snapping to those parts back in 2022 (I think it was released with the second 1.7 alpha).

So You are probably using an old LDCad version.

You can also update just your snapping information by downloading the latest version of the shadow library:
https://github.com/RolandMelkert/LDCadShadowLibrary

Just use the 'code' zip (Green button on the github page) and point LDCad's prefs/LDraw/Search paths shadow location at it.
Rename the zip to csl if you're using 1.6d or older.

ps: I recommend upgrading to LDCad 1.7 Beta 1 (and the latest github shadow) though, don't mind the beta stage it is very stable. (Even more so than 1.6d actually).