I am new to this site ( just found it by accident ) Any way I have bin a DL for a long time but never did much about it till last 6 or 7 years or so. I have bought my plastic pants online. But they never fit the diaper right ( the diaper came up higher than the plastic pants I had so I ended up with a wet bed in the morning. So I set out to make my own pants and this is what I came up with.
I took an old pair of plastic pants and carefully cut them apart to use as a pattern and to reuse the elastic for the legs and waste band. Then I cut the side seems and layed it out on a flat surface and layed a bath tow over it and toke a steam iron and went over it to flatten it out now this is the pattern to cut out the plastic pants or you could use a pair of underwear as a pattern just remember to cut it at lest 3 or 4 inches larger. Now get a vinyl mattress cover from walmart and a vinyl pool repair kit. First glue the sides together and let it set over night but remember the glue has a strong oder to it. Now cut a piece of cardboard to fit tight across the openings and put the elastic over the edge about 1 1/2" and put the glue below the elastic and fold the top edge on to the glue carefully and let it set over night and it should work you might have to experiment with it to get the results you want. I used foam board instead of cardboard its more ridged, and if you don't have elastic from and old pair of plastic pants you can get it from a fabric store or walmart or kmart. Good luck with your project I hope this helps.