Step 1: Deciding on a pattern
Step 2: Taking the amp apart
Because I cannot cover every single amp or cab here are some vague steps I found useful:
1. Remove back panel from amplifier
2. Remove reverb tank and any wiring from the amplifier to the reverb tank.
3. Unscrew the speaker and remove
4. Unscrew the wood the grille cloth is attached to and remove (can be difficult, but can be done with everything else removed!
Next step, what to do with the stencils!
Step 3: Cutting the stencils
1. Cut the outline out - this will be sprayed in white first
2. Cut the black parts out - this will be sprayed second in black
Secure the first template to the amp and spray with white (picture example below of how it should look)
Remove first template, put on second and spray with black. Make sure you align the templates up properly!!
Pictures of how it looks are below.