A Secure Seatpost Brompton Bung!

I made a post before about this before but I've refined it and released it for sale. Essentially it's a seatpost bung/butt plug that protects the bottom of your seatpost and acts as a stopper that prevents your folded Brompton from rolling which always seems to fall out.

Since the last version I shared, I changed the materials, the dark grey stuff is a foaming TPU that is lighter weight and grippier than the previous TPU I used. That means I achieved my goal of making a seatpost bung that is lighter than the original (9.5g) but still secure enough to hold a pump and other tools/accessories inside without worrying they will fall out.

I also made a couple sizes to support third party seatposts. Some seatposts don't have the flared bottom so aren't compatible with the seatpost height adjuster so I made a bung that adds a lip to add that functionality back.