This tool facilitates the spreading of butter by making it like "using school glue" avoiding the use of knifes and distributing butter equally along the bread. Ideal for children. Has been designed and optimized for be easily printable on 3D printers and require a minimum time of adjustment and assembly. (assembly and usage instructions in instructions tab) Hope this tool is useful. Happy Building! For assembly first print all the parts, it is recommended to print the main screw and the main body alone each other in order to avoid ooze and bridging problems (since they had threads they are highly sensitive to all that stuff.) i recommend a 0.1 mm layer setting for this print. Once you have all the pieces print check that everything fits; the extruder should move with a little bit of friction inside the main body but not too much, a little bit of smoothing with a file on the sides of the extruder part is recommended. Assembly: 1-Insert the main screw on the main body and screw it in till the end 2- attach the extruder to the main screw with the "C" pieces, the main screw should rotate freely attached to the C of the extruder. 3- while you screw in the main screw guide the extruder until it gets inside the main body and moves correctly. For inserting the butter: 1- pull back the extruder with the screw until arrives to the desired volume. 2-cut the butter and insert it inside the cavity 3- use the compactor to evenly compact and distribute the butter inside the cavity. It also comes with a cap for storage reasons (you know, butter tends to be sticky as hell) Happy building!