Here are the 3D print files for my desktop maze. I've also included the FreeCAD design files. A maze can be built on any flat surface.

There are three different posts; corner, edge and center. They fix together with small connectors.

The base of each cell is a piece of black card just over 1mm thick with 6mm squares cut out of each corner.

The walls are two pieces of 5mm white foamboard from Hobbycraft with 3D printed end pieces. The foamboard is slightly thicker than 5mm but I will try putting a piece of card between them to get the thickness closer to 12mm.

It has the advantage that the maze doesn't have to be rectangular.

The test maze below was put together on a kitchen worktop only 40cm deep.