I've had luck producing my own water slide decals with inkjet water slide decal paper.
You can choose any font on your computer for the lettering and you can also print out graphics.
It comes in clear and white background so you can print anything in black and color on the clear and anything requiring white on the white background.
The biggest drawback I have found is you can't print white lettering, well, if you have one of those special printers which can print white ink then you may be set for white lettering.
If you want the tick marks or numbers listed on the controls you will need to work with a graphics rendering program to make them wrap around in a circle. I use Inkscape because it is free and there are a lot of resources on the internet in regards to tutorials on how to accomplish just about anything.
The paper i use is from a place called the Bare Metal Film company. The paper is the Experts Choice paper. Here is a link to their page :
http://www.bare-metal.com/Experts-Choice-Decal-Film.htmlI've also tried rub on letters and a product called rubonz, though I would steer you clear of it. It was difficult to separate the decal from the backer paper and I ended up destroying half of the decals I printed and ended up having to redo a paint job on an amp due to them. Only a good product if you don't want quality.