Here is a TA12 transport shuttle (from thingiverse stl file)

A very easy files to print, I do recommend for beginners

Maybe needs to scale up a little, I think this was designed for 28mm

I did modify STL file in order to add a 5mm LED + a 3.3v battery holder and a micro switch

The painting job is a little bit rough and will require some wheathering (didnt paint models since 20 years)

Let me know your comments