I was tired of using a general tray for my nozzles and tools to change nozzles and wanted to better utilize the left side of the core one. 

I created this model for holding nozzles and the required tools to change nozzles for any core one printer (or any nextruder really) but fits well in left side of core one.

The holder has openings so you can see which nozzles are stored.

It has slots for any 2mm magnets to be inserted so it can be placed really anywhere that is magnetic.