A decent split keyboard with Bluetooth would be a great hardware project, similarly a nice trackball. Building a quadcopter might also be nice. A one/two whee

A decent split keyboard with Bluetooth would be a great hardware project, similarly a nice trackball. Building a quadcopter might also be nice. A one/two wheeled selfbalancing robot. A lawnmower robot that doesn’t maim small animals like hedgehogs. A small submarine or sailboat with remote control.