Not sure if anyone covered it before,but here is my way of making lenses.
Here is what you'll need: a torch, pliers and leftover sprue.
![](http://i1059.photobucket.com/albums/t436/2750709/E975BB67-AA93-46E7-92D6-7E5D74B89555.jpg)
Heat the sprue
![](http://i1059.photobucket.com/albums/t436/2750709/860CC32A-C1B7-489E-BC36-6438185081F6.jpg)
to form a bead, careful not to let it catch fire.
Gently squeeze it with pliers.
![](http://i1059.photobucket.com/albums/t436/2750709/C3A0D2A1-2558-42AC-868A-58FC8C5AE522.jpg)
Cut it out and file to shape, round the sharp edges with sand paper.
![](http://i1059.photobucket.com/albums/t436/2750709/CF64F0DD-FF64-4724-96AA-31FC31A952EE.jpg)
Mount onto besel.