Star ratings for Project skill levels are as follows:

   Does not require any soldering or any actions more complex than measuring, cutting, drilling, and gluing. Or, requires simple digital modeling and ordinary (“quick print”) 3D printing.

  A small amount of soldering may be required, but no circuit boards will need to be made, and no microcontrollers must be programmed. Or, requires simple digital modeling with an imported file and third-party extension and ordinary 3D printing.

  A simple design will need to be made, which may use a small stripboard. You should be reasonably proficient at soldering and able to use a multimeter. Or, requires you to program one or more microcontrollers. Or, requires advanced digital modeling using third-party extensions and flexible 3D-printing filament.

  A complex design must be constructed, requiring the ability to solder a stripboard. Or, requires advanced digital modeling and analyzing using third-party extensions and advanced 3D settings. In both cases, some mechanical construction is necessary.