This is a really easy and a fun project especially if you don't sew !! :)
I made this onesies for my daughter's first birthday.
This stuff is so great since I don't sew! It is a called Heat n Bond.
I got it at Walmart but most craft or fabric stores will have a similar version.
Again you will cut the shape out of the heat n bond that you need.
Follow the instruction on the back.
Once the material is ironed on your onesies, just take some embroidery floss
and and go around the big circle and the number to make it pop.
I also made 12 onesies with #1 thru #12 on it for my nephew for a picture each month til he is one. There are so many possibilities for onesies or T-shirts. You could make Mickey Mouse ears for a Disneyland trip, Christmas shapes to match PJ bottoms, holiday shapes,
animals, names, the possibilities are endless!