I know this doesn't count as “purge” waste but I find it also very wasteful to throw out so many chunks of solid filament after a flow rate calibration. I did one yesterday to check the 0.8 nozzle with new ABS and vowed to do something useful with them for once. After a some thought and a few moments of smashing them together like a chimp learning shapes, it came to me…a butterfly!

The print is two separate halves of a butterfly with connectors on the backside that can attach to the calibration pieces. I was optimistic thinking I could have the pieces connect tight enough to not need glue, but the over/under extrusion really changes the dimension of each piece so you will have to glue them for best results (so ya, I probably didn't need the connector parts in the end but oh well).

The butterfly will print face down and has a pattern that is easy to paint in Bambu Slicer. I used Bambu blue galaxy, Ziro matte neon, Bambu basic silver and Canadian Filament's copper penny colour. The bottom pattern is set to concentric as I wanted to see how a larger section of this pattern would look in the Ziro neon filament (and I think it it's pretty, pretty, pretty good). Plus I think concentric just matches the butterfly design well regardless of filament type. I turned off the prime tower in the profile since we are trying to minimize waste here and because colour bleeding can't hurt here anyway. The butterfly itself is only 1 mm thick so the calibration pieces will add most of the strength. Bonus also is that the more flexible middles (the part with the calibration number) will be in the area of the butterfly body so conceivably you could flex it (or heat it with a lighter and actually bend it) if you like to add a bit of “flap” to the wings. 

See the photos for assembly. You can rearrange the order of steps however you see like but that is the basic idea. I used hot glue for all of it and added a small magnet to put in on the fridge.