HookJab's design is great, but I use my pinecil on the go frequently so it lives in it's travel case but I use the heatset inserts less frequently and rarely away from my work station.  I remixed the design to make it more compact, and also there was enough room to allow for one of the mid sized tips to stay installed if you frequently use one size.  In my case I almost always use M3 so that practically lives on the heater.  

Update:

According to @gezepi_415570 the M4 and M5 spots were too small so there's an updated version with those spots increased.  Check the diameter with calipers, if the M5 is bigger than 6.8mm use the resized version.