The little plastic bag clip that held our English muffin bag closed broke, so my little boy and I designed a new and improved one. This one isn't so hard to get off, and the fish body is just the right size for a firm grip.

You can scale it with the OpenSCAD file. (Once customizer allows importing dxf files, you'll be able to use that, too.)

I added an image that shows how the design progressed on the whiteboard. My boy was the primary artist. It started off with a clasp mechanism, then took a turn toward simple and practical, and finally it got a little wild. There's another one I left out that had the clasp at the end of the trunk or a very large elephant. (We decided that would wouldn't fit on the printer.)