This is a spacer/insert for use when using a Lamy EMR grip/module with a Lamy Safari Vista body.
This is not a functional piece, or needed to build this custom EMR pen, just fills out the empty space with a color of choice. Could also add a bit of weight if desired to the ¼" long hole in the bottom of the print (or use the hole to get it out with a screw or otherwise if it becomes stuck).
I used about 13mm of heat shrink on the smaller end, which causes it to fit snugly, and also creates a “cushion” on the end (by being longer than the insert) to allow it to be tightened down completely without rattling.
Parts, for those interested:
The author marked this model as their own original creation.