This is pretty straight forward if you can cut a straight line. Glue your shiny vinyl onto a sheet of 1/8" foamie with spray glue (I recommend the heavy-duty 3M stuff). In this instance, I'm using some pretty heavy-duty black vinyl - like the kind a vintage diner would upholster their booths with. I also prefer this vinyl because its cloth backing will adhere well to the foamie.
Trace your pattern onto the back of foamie (my bolt is about 3½" high and 2" wide). It's actually Ruth's design. Just make sure you reverse your pattern when you draw on the backside, so it'll be the right direction on the vinyl side! Trim very carefully - long fluid cuts, not chewed-up short snips.
Glue your pin-back on and you're done! I like e6000 - it gets between the holes of the pin-back real good.
