I have a habit of putting chuck keys etc on top of the headstock, and have done so since I started using lathes. The difference is that when I started the lathes were quite a lot bigger than my hobby machine and so included a tray to put chuck keys etc.
There is just suffícient room for such a tray on the C3 and I made a shallow tray. The sides are 10 mm and the tray is made of 1 mm steel sheet. The corners are sealed with epoxy glue for user safety and finally painted in the shop color – guess mine.
Two strips of double stick tape, the thick carpet type or those double stick foam bits are good to use to fit the tray to the headstock. The tray is sized to fit between the chuck protector and the left end of the headstock and be as deep as the headstock allows.This gives sufficient room to store the other set of chuck jaws and som other bits including chuck keys.
A small but very useful addition in my mind.
BR
/Peter