Instructables
Picture of Adult Onesie From a T-Shirt
For those of you that don't know a onesie is a t-shirt with snaps in the crotch.  You can pick the up everywhere for babies but for an adult you need to order form a specialty dealer.  They normally start at $25 plus shipping and go up from there.

Step 1: Materials

Picture of Materials

For this project you will need.

1. A T-Shirt a few sizes too big.  I wear a size large and used a 2XL
2. A t-shirt that fits for a pattern
3. Scisors
4. Sewing equipment.  I sewed mine by hand but a machine would be faster.
5. Pins. Lots of them.
6. A marker or chalk for lay out.
7. A tape measure
8. Snaps.  I used sew on snaps but Velcro could also be used. (9mm shown in picture have since been replaced with stronger 21mm)

Step 2: Layout

Picture of Layout
layout2.JPG
layout3.JPG
layout4.JPG
1. Turn the large t-shirt inside out and spread out flat.

2. Lay the smaller t-shirt on to of it with the tops aligned

3. With the marker or chalk draw a line straight down from the armpit seam of the large t-shirt to the bottom along the smaller shirt on both sides.

4. Take your round object and trace a radius from the line you just drew to the armpit of the t-shirt.

Step 3: Pinning

Picture of Pinning
1. While keeping everything flat put many pins along the lines on both sides all the way to the bottom.

2. Carfuly slip the shirt on and decide where the split for the legs will be and mark it.

Step 4: Sewing the sides

Picture of Sewing the sides
sewing2.JPG
Sew from the armpit all the way down to the mark you made for the split.  It is a good idea to re-enforce the bottom of the split with some extra stitching.  I use a double row of hand stitching.

Step 5: Cutting

Picture of Cutting
Leaving a centimetre or so of extra cut along the outside of you seems.
 
Remove these adsRemove these ads by Signing Up
I have come back to this again and again over the years to make interesting onesies, including Captain America, Tigger and a light up Iron Man Arc reactor.

This is freaking awesome, whatever you want to use it for. Only thing is, if your fairly tall, t-shirts do get wider, bu not a lot longer all the time, so you will need a VERY large shirt. Or a small adult.

Many thanks for the idea though!
I want to make onesie for the Rugby World Cup! imagine... crashed out in the lounge with all your rugby buddies cheering on your favourite rugby team...wearing onesies of your country! a south-african onesie of springbok and RSA flag design, a nz onsie of the all black and nz silver fern or nz flag design, and the english supporters sitting there wearing the england rose design... and Australia? well there is bound to be at least one aussie with ya! aussie flag / wallaby design for be cool! first i have to see if spotlight or anywhere else had the material coz i dont want to ruin a tee-shirt. lol
I have a 21 year old mentally and physically handicapped son and he is constantly putting his hand down his pants and ripping his diaper. To buy these shirts costs approx $25 each. I can sew and saw this and thought why not try making my own. That's why it's handy and useful for me. I didn't care for having to purchase a membership just to download the pdf file but it was only the cost of one of the ones you buy, so if it works its a win win situation.
lqrpnk4 years ago
This is perfect for my constant worry of everyone behind me seeing my crack when riding (motorcycle, that is). Genius!
mrmath4 years ago
Why would you want an adult onsie?
logghi mrmath4 years ago
Because they're awesome. Hush. You know you want one ^^
nieks4 years ago
Great idea, though most people won't find a use for it.
tom_bom4 years ago
why wouldn't you? :P
seconded ^^