The filament is clamped by the clip itself, so it's quick to attach and remove.
The gap is a bit narrower than Madox's original, the original was a bit loose on my spools. I also added a small chamfer to the bottom edges to lessen the elephant's foot effect.
You might want to print it in PETG to get a bit more play before it breaks. Also, I've noticed that PLA deforms over time making the gap wider. One of the clips i printed before (1.8 mm gap) now measures more than 3 mm. Using PETG should fix this.
UPDATE 3: Added an even tighter version (1 mm gap). Print this in PETG and it should be perfect for any spool.
UPDATE 2: I got some feedback from maker alexculli that it didn't fit well on some spools that are filled up close to the edge of the flange. I shortened the part that sticks down below the filament groove, this should help a bit. I also tested the tighter version in PLA and it seems to work great, it doesn't break on any of my spools, so the standard version now has the 1.8 mm gap. You can still print the wider version if you have very thick flanged spools or very brittle PLA.
UPDATE 1: I hate to have different versions, but some of my spools (Fillamentum) are only 2mm thick (past the 5mm outer rim). I added tighter versions that have a 1.8mm gap. The normal version is 2.5mm. If you print with PETG or some other material that can bend more than PLA, the tighter version might work on thick flanged spools as well.
Please post a Make if you make this!
100% (all perimeters, really)