Clip to fit on spools of filament that are an indicator of spool moverment visible from the front of the K1, recently lost a long print due to a badly wound new spool of expensive filament.

Murphy's law said it was never going to be a small print or one using £11 per spool PLA, TPU, ABS etc but a 12hr print using a £90 spool of specialist material.

Apart from that failure I like the spool at back, width on my desk more valuable than depth.

So attach a clip or several clips so that you have visibilty, designed for small rubber bands, but as is the case I can not lay my hands on one, so pictured with largest & less largest I had still works fine.

use them for any reason they are handy and have already found several unintended uses today.

A spool dial indicator of 260mm diameter was my first thought but many people do not have the 300mm bed to print a 260mm donut to clip on spool. Printing  interlocking segments of different colours may have its advangages. My first test donut will use bronze rainbow PLA I have for another project, hopefully will show enough colour variation to make motion obvious.