3M brand transfer adhesive sheet for attaching acoustic guitar pickguards 

Make a pickguard out of any thin plastic or timber sheet

- 8" x 10" (203mm x 254mm) sheet
- Ultra thin
- Extremely strong
- Clear
- Pure adhesive (no tape backing)
- Waterproof
- For plastic or timber pickguards

This is the best adhesive for attaching acoustic guitar pickguards and is used by many top guitar manufacturers. It is perfectly clear, thin (3-5 mils.), extremely aggressive, tenacious, heat resistant (up to 200°), and waterproof. 

Simply unroll to expose the adhesive, apply to the back of the pickguard, trim away the excess with a sharp knife and (after removing the protective layer of wax paper) press firmly down to the surface. Once you try this method, you will never want to use anything else.