I thought this was a silly idea when it occurred to me but it was too easy to make these handles, nest the bags, and try it. Now I have a bunch of them around because I found them quite sturdy and re-re-reusable.
Step 1: You will need
8" Velcro - both hook and loop parts
a bunch of clean enough reusable same size plastic bags
Instead of sewing, you could use iron-on adhesive if you have one that's strong enough. Or you could use sticky back Velcro. I don't have much experience with these methods for this kind of project.
Step 2: Cut materials
The fabric should be robust enough to handle being handled a lot. It could probably even be made of several layers of thin plastic from extras of these plastic bags.
Step 3: Sew Velcro to Fabric
Zigzag the edges to keep them from unraveling.
Step 4: Test Handle
Even after making so many of these, I can still do this step wrong :)
Step 5: Install handles
Step 6: Test out your bag
Use as a trash can and cut out the inner bag to throw the trash away. Your next trash bag is ready and waiting.
Use at home, in the car, camping.
These handles also make functional cable ties.
I look forward to hearing how you might use these or modify these. Have fun!