The STEMFIE construction set is scalable. You can either increase the size of the parts in your slicing software to make larger prints resembling Duplo building blocks, or you can reduce the scale to yield more parts per filament spool.
The scale for STEMFIE at 100% is designed to print optimally at 12.5 mm per block unit (BU) using standard settings for 3D printing (0.2 mm layer height and 0,4 mm nozzle).
In this test, the small STEMFIE desktop catapult is printed at 50% scale, resulting in a block unit size of 6.25 mm. It is more challenging to render all the details needed for the parts to fit well at a smaller scale. Therefore, I recommend lowering the layer height to 0.1 mm, which was used for printing the model shown in this blog post's image. For optimal results in 3D-printing STEMFIE parts at this reduced scale, I recommend using a smaller nozzle diameter than 0.4 mm.
The 3D model and build plate files for this test can be downloaded from this link.