A universal marker cap - the solution to prevent drying out the marker tip when you lose the original cap
I encounter this problem often - the caps of my markers get lost and I can't find alternative ones. Then they get dried out and can no longer be used.
I therefore designed this universal cap, which can be used with various sizes of pens and markers. The cross section of the model with diameters included is given below:

The author marked this model as their own original creation.