I have an idea for a simple rotary attachment/addon. You wouldn’t be able to engrave a rolling pin or baseball bat, but maybe a pen or set of drumsticks.
It would be fairly simple to build, you could even use your new glowforge to cut the gears! Basically it is a micro stepper motor attached to a pair of rollers. An arduino attached to the motor and an IR sensor. It doesn’t need any physical connection to the glowforge. My idea is that you use the laser “defocused” to send a pulse to the IR sensor that tells the arduino to increment one step. The glowforge software would have to add the option to move the laser over the sensor after each pass.
Forgive my basic modeling skills. I just downloaded 123D Design to practice with until my glowforge arrives.