The adapter is made to fit the pen that is used and it slides into the tool body, a quick and easy way to provide spring tension is to use a rubber band. Takes 1 min to assemble and use as a regular Zund UDT tool.
This is a simple tool that’s quite useful to have when you are cutting patterns in continuous batches and you want to label all the parts. It follows the same basic dimensions as all Zund tools and is very easy to print.