Fuji X to Canon EF adapter with lock

Assembly tutorial by original author :

Two versions of the lever, one fully 3d printed and second that uses M2x5mm (or longer cut to size) screw as a locking pin, it may scratch your lenses but is stronger and more reliable.
 
To secure the screw in the lever you can use some leftover plastic from supports/skirts and melt it with solder iron or you can leave it only screwed in but it might become loose because plastic there is quite thin.