This project only cost me about $4
Supplies
Step 1
First thing I did was I drew the bones onto the pants, and then painted everything else but the bones with my black fabric paint.
Step 2
Next I cut the shorts to size, they were a bit long so I had to cut about 5 inches off each leg. I then lined up the waistband of the pants and the shorts and stitched the short legs down onto the pants.
Finishing
After it was all stitched down, I went back and cut the pants a little ways up from the stitches, that way it was just the shorts waistband and pant legs. And then the pants were done! You could also add either yellow fabric or yellow fabric paint around the waistband to make them look more like Papyrus, I didn't simply cause I knew his hoodie would cover his waistband, and also the waistband is really stretchy and I didn't want to lose the stretch by adding fabric, or making it stiff with fabric paint.