Rationale:
I wanted to be able to use https://www.prusaprinters.org/prints/26557-wooden-train-brio-ikea-to-duplo-adapters-mini on Duplo build plates, but the length of the various Brio and Melissa and Doug tracks doesn't correspond to the grid on Duplo.
I started off with a Duplo brick generator and modelled a part that suited my purposes.
Requires:
M3x20mm socket head screw (such as included in the spare parts with Prusa MK3S)
M3 hex nut (such as included in the spare parts with Prusa MK3S)
Printing Notes:
I printed these with support.
Assembly:
The author hasn't provided the model origin yet.