My take on the Time-Turner from the Harry Potter series. I have included materials needed here, but I also did an instructional video on how to make and assemble this:

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Note: The hourglass portion is not 3D printed. I have listed my Etsy source for the hourglass and I also listed the dimensions of that hourglass on the BOM (6mm Diameter x 28mm Long) if you want to put something else at the center.

STL quantities to print:
Inner Disc, Time Turner {QTY 1x}
Middle Ring, Time Turner {QTY 1x}
Outer Ring, Time Turner {QTY 1x}
Knob, Time Turner {QTY 2x}
Holder, Hourglass, Time Turner {QTY 2x}