Potty training is a continual adventure in our house. My daughter will be three in February and is bright, articulate, creative, but less than in touch with her bladder! (Luckily, bowels are fairly consistent at communicating the need to sit on the potty!)
I experimented with some patterns that I found online but they were too big and didn't stretch right. My picky daughter wouldn't wear them. OK, to give her a little credit, who would want to wear uncomfortable undies!
I started with a onsie that still fit, but was heading for the goodwill. I cut it off at the waist. Then I cut the snaps out of the crotch.
And sewed them to the side. I cut out the whole "strip" of snaps, not individual snaps. I only did one side, but later realized I could have used snaps from the back of this onesie for the other side. In my next pairs I omitted this also because my daughter insisted on unsnapping them and then snapping the side each time she pulled them up and down. They were just more hassle then they were worth!
I initially intended to just sew up the crotch as as but, I wasnt sure without the snaps if the legs would be big enough so I added more length to the crotch. I found out after I finished making them that extra length wasn't necessary, so on the next 3 pair I made, I omitted that. I used PUL as the extra fabric.
I made padding for the panties with 6-8 (depending on the pair) layers of flannel. I also included a layer of PUL (cloth diaper fabric) for some leak protection.
I sewed the flannel together first, then to the panties. I made half the layers smaller and the other half a little bigger so it wasn't so bulky everywhere, but still had protection.
I finished of the top and sides with foe (fold over elastic used to make diapers or diaper covers). The next ones I made did not need foe on the side because I didn't add any extra fabric.
Lucky for me my daughter wears them and likes them! Also usually when she has an accident her pants stay dry most of the time. If her pants do get wet the pee doesn't make it to the floor.
This is my daughter in the second pair that I made her. I think they turned out better than the first.
If you try this, please let me know how it works out or if I can make the instructions better. The whole reason I started this blog was because other peoples blogs and tutorials were so helpful to me I thought if I could help someone I'd love to!
Post Edit: With the top of the onsies, I've been using them as tees for my 1 year old to wear at night with her wollies under her fleece PJ"s since onsies aren't an option.