A mechanical stress-relief keychain designed as an internal combustion engine. Its compact size makes it perfect for everyday carry on your car or home keys, or even as a stylish accessory hanging from your rear-view mirror. Easy to print and simple to assemble — a great choice for a quick and impressive 3D printing project.This model can be easily printed on any FDM or resin 3D printer. PLA filament is recommended for the best results. You can print the parts in different colors to highlight the mechanical elements.Assembly requires only cyanoacrylate glue (super glue).