Hey Geekhack!
I'm a fairly new user here but I thought I'd give key cap templates a go after seeing a few people asking for them.
I've based them off of the measurements given my WASDKeyboards. I am assuming these are the sizes of the face not including the draught. If the draught is included in these measurements then there will be around 0.1" that need to be added to the templates on all sides.
Some of them will be off by ~0.1" at most I would hope. The sizes are real measurements so a regular 1x cap is 0.71" by 0.71" and this accurately represented in the image.
These are by no means superb quality and are really, really basic but they act as a testing area that people may use if they have ideas for keys and want to see if they'd fit on the key cap.
If you'd like me to add other sizes or fix up any mistakes I may have made please do let me know!
Direct link to image is here:
http://i.minus.com/ib0LQjpFFNPcCT.pngHere is the template:
Dave.