This was interesting, different techniques, including using the poly, which I thought many of us would have anyway.
https://youtu.be/xHOWUR8vTvo
Seems to me the crude transfer using just an iron would be really handy for accurately marking out where to drill holes etc.
Build #1, failed solid body 6 string using neck from a scrapped acoustic (45+ odd years ago as a teenager!)
Build #2, ugly parlour semi with scratch built body and ex Peavey neck
Build #3, Appalachian Dulcimer from EMS kit
Build #4, pre-owned PB ESB-4
Build #5, Lockdown Mandolin
Build #6, Sixty six body for Squier
Build #7, Mini Midi Bass
I tried it a couple of years ago and it's hit and miss. Some turned out ok. The secret is when the image starts to come through stop rubbing the paper off. It's tempting to keep going to get it perfect but the image starts rubbing off then. Ok if you want a aged look. If you wet it once the paper is rubbed off that will give you a idea what it will look like with a clear coat.