Place the spoon next to the Altoids tin so you could measure or estimate where the cut should be. Remember that the cut spoon should fit comfortably in the tin without sticking out of the tin.
Step 1: Attach the Spoon to the Binder Clip
Cut a strip of duct tape about 1.5 cm thick. Then tape the spoon to the binder clip and make sure it does not slip. It is also a good idea to secure the bond with a rubber band tightly wrapped around it.
Step 2: Make the Binder Clip Support
The binder clip support is what will anchor the binder clip to the bottom of the tin so it won't move when fired. The support could be made from a used gift card or any other similar alternative.Make sure the intended support fits nicely in the tin. Then cut an end of the card that is less than 1cm wide. This piece should be able to slide into the binder clip and be parallel to the tins bottom.
Then you use the rest of the card as the other part of the support. Simply place it above the the on top of the bottom binder clip handle.
Step 3: Glue the Assembly to the Tin
Use your trusty hot glue gun to glue the assembly to the bottom of the tin. Be sure to generously apply the glue to the tin and press down the catapult assembly. ( be careful not to burn yourself with the hot glue gun)