This is a pen depth setting tool for my Gondola and pen holder (pen collar).
The idea is that you set one pen to the correct depth and use that to set the depth on this tool. Lock the tool with the locking screw and you can then quickly and easily set the correct depth of the other pens.
See http://www.thingiverse.com/thing:1393028 for pen holder (pen collar) and push fit Gondola.
See http://www.thingiverse.com/thing:1393182 for a pen holder to hold multiple pens in their individual pen holders (pen collars) - I think I need to rename the push fit pen holder as pen collar...
Anyway, this is a work in progress as this was supposed to be part of the multi-pen holder but I haven't finished it and my printer is making a mess of it so sizes might need tweaking. I'm including it as part of the release of all the files I've been working on for a while now.