Trace the templates. Trace the cupcake flag templates from Cut up This Book! Special Occasions onto tracing paper, then cut them out. You could then trace them onto upcycled cardboard for a sturdier template, but keeping them on tracing paper will allow you to fussy cut your fabric scraps.
Stiffen the fabric. For my daughter’s dinosaur-themed birthday party, I used a scrap of novelty fabric that used to be a pillowcase, and then a pillowcase dress, and then who knows what? The fabric needs to be stiffened, so iron it onto interfacing, or, for a more eco-friendly solution, stiffen it with homemade spray starch by painting it on or soaking it in it and then laying it flat to dry.
Cut out the flags. Novelty fabrics are my favorite for small projects of this nature, since you can fussy cut the perfect little graphic from them.
Trace the templates in chalk onto the fabric, then cut them out with fabric scissors.
Glue. Using a strong white glue, such as Aleene’s Tacky Glue or another similar brand, spread glue on one inside half of each flag, place a toothpick or flat-head pin along the middle, then fold. Press each flag together for several seconds, until it’s clear that the glue is sticking well, then set the flags aside until the glue is completely dry and cured.
The flags are ready to be used as soon as the glue is dry.
If you’d like to re-use your flags, I suggest using a flat-head pin for the flag pole, since it’s easily wiped and sanitized–just double-check that the glue is still holding well before each use, since nobody likes a lost pin in among the cupcakes! For this batch of dinosaur cupcake flags, however, I did use toothpicks; these are still re-usable, as long as you wipe them down more carefully and don’t use them with any food that might stain the wood.
Full Disclosure: I received Cut up This Book! Special Occasions for free, so that I could make stuff using it.