Since I'm making a lot of these for my build I decided to write a little tutorial on how to make these little things.
1: Lighter, can also be one of those lighters you light sigarets with, but I couldn't find another one.
2: Aluminium plate, or something else that doesn't melt when heated
3: Knife
4: Electric drill
5: Piece of sprue
First take your electrical drill and drill a hole in your aluminium plate (this hole will have the same diameter as your rivet)
Second, take your piece of sprue and heat it with your lighter.
Then, when your sprue starts to melt, push it through the hole you made in your aluminium plate.
The other side should look something like this:
(It isn't that visible in the pic, but if you look really hard you can see the rivet sticking out of the hole.)
Wait for the plastic to cool down and pull your sprue out.
Next step, take your knife and cut off the little rivet.
Last, collect them in some kind of container.
After a while you'll get enough to actually do something with those lilttle things.
I hope this has been some usefull information to some people :)