I know this type of topic has been raised many times before. I know, because as an ex-lurker here, I've read many stories on different posts or threads about this topic.
But as a lurker, I always wanted to chip in but couldn't. So here's my chance! If you don't want to reply fine, but I really want to tell someone about my classic homemade creation.
I put on 2 pairs of briefs, with a folded thick hand towel, forming a big liner down the middle but unfolded in the butt between the pair. Then I use a particular bin liner bag, which is either translucent white or yellow and lightly scented, and about 2 foot or 600mm deep, which I step into and force my feet through the bottom corners, then pull it up. I then fold it down, and tuck it in firmly all around the leg bands and waist.
The end result is a thickly padded arrangement, which feels so much like a real diaper does, and is also surprisingly waterproof and realistic looking. It does look like a real diaper/plastic cover combination!
Once again, apologies for starting this again, but I've wanted to say that for so long!!