photo/info credit: nylon,np
You'll need: slip, a pair of undies(for tracing), scissors, measuring tape, needle & thread, snaps, spray fabric sealant
step 1: Find a cute knee-length slip.
step 2: Decide how long you want the shorts portion of your onesie to be: Midthigh modest? or rear-skimming skimpy? Don't go too long or you'll risk "an MC Hammer kinda thing."
Using the tape, measure from your shoulders to where you'd like the shorts to fall, and then mark that same length on the slip.
step 3: Lay the slip flat, and place the underwear at the mark. Trace along the curved holes of the undies onto the slip, and then cut along the lines.
step 4: Sew snaps to the hanging material that will serve as the crotch of your onesie. Snap together and, if desired, spray sealant on the raw edges for a "frayed Lanvin look."
step 5: Time for you to romp around in your new playsuit!