No-supports version, perfect to print in PETG.
Print instructions:
To assemble, just put all parts together, super easy.
Be aware that the square version has a larger opening, so it can fit slightly larger bags:
https://makerworld.com/en/models/81831
STEP file included. Feel free to remix and share, but please use the attribution feature.
Internal spring based on obijuan's design:
https://www.thingiverse.com/thing:21234