Here is a simple 2 step, 5 minute t shirt that you can "make" to reuse baby onesies.
My babies no longer use the onesies. Mainly because we cloth diaper and they're a pain and their diaper covers are way too cute to cover up!
Just simply put the shirt under the machine and put the needle down. Here I used an overcast stitch since i have the option on my machine. (See previous post if you don't know if you do!) With the needle down through the shirt, pull on the fabric infront of the machine just enough to stretch it almost all the way. You don't want to pull it completely because then it won't move under the needle as your sewing and it will stay in one spot. You have to keep it stretched as your sewing so that it will ruffle up. :)
You can also do this with the arm holes if they aren't hemmed. It all depends on the brand shirts you buy.
Now is a great time of year to buy these second hand because they are "short sleeve" and considered summer stuff.
You can add appliques and/or tye dye them if they have stains!
Ruffles with tulle around the bottom is cute too!