This is how simple it is to make your own safety button, in this case a brass oversized one.
1, Get hold of some 7mm brass bar.
2, Cut a piece just over the length you are going to need.
3, Use another button as a guide for measurement.
4, Put the length of brass bar into a pedastel drill.
5, Set drill off and using a file turn the bar down to about 6mm.
6, Once down to size mark out the slot marks.
7, Get a hacksaw blade and saw into the marks down to the depth needed, about 3mm. Use a file with the drill spinning to finish it flat.
8, make sure with an oversized button to extend the oversized bit to account for the cylinder diameter.
9, Check to make sure it works the put brasso onto it and polish in the drill again.
Takes about 30 mins to do once you get the hang of it and saves you money in buying one as well as the enjoyment you get in making your own.
https://www.flickr.com/gp/124581931@N06/15kP0f
https://www.flickr.com/gp/124581931@N06/4f2i8F
https://www.flickr.com/gp/124581931@N06/2c9740
https://www.flickr.com/gp/124581931@N06/Y87671
Hope this is of use to some readers.
Fozzy