Hilbert curve marble run

This is a marble run based on the third order Hilbert curve. It is an easy print that requires no support. It is designed for 12 mm marbles or steel balls. I originally intended to add a motorized lift to raise the marbles from the exit point back to the entry. I may still do that, but my 3 year old grandnephew happily plays with the model for hours at a time as it is. I think small children may enjoy it the most when it is not automated. I printed the example with PLA matte, but it should print equally well with any kind of PLA or PETG.