there are actually endless things you can do, you just have to be
creative. you have to make sure you have a catch and a joint. both
should work well and be secure. in addition, it should be simple for
your potential buyer to use.
is making your own pin stem, make sure the wire is hardened and of a
sufficient gauge. (18 or 19 gauge) you can use white gold if you
plan on heating the stem at any point so it will retain its
hardness, but if you are using sterling, you can draw the wire down
inorder to harden it. in this case, you cannot heat the pin stem
again, but you must rivet it or otherwise secure it in place.
perhaps you use s imple curved wire for the catch. perhaps you use a
small piece of 10g round wire and cut a small slot in it to receive
the pin stem. perhaps you construct a catch out of sheet metal in
the form of a curve or even a box. saw or carve out an opening for
the pin stem.
for your joint, you just need to make sure the pin stem is able to
move. does it move by spring action of the pin stem itself? does it
move in a hinge way? do you actually make a small hinge? you can
bend the pin stem at the end to make a foot that rests on the actual
pin back and then rivet this in place in between a sheet meetal "u"
of some sort....
the options really are endless, i think you just have to really look
at how the clasp works in its basic form, and then go from there.
experiment! but, as i said before, it is very important that the
clasp is user friendly.