I don't like the prices they charge for the speed controllers from the well known manufacturers, and it seems you can get most component parts quite easily these days, so I thought I would build my own. So, here it is.

(I updated the design to hold onto the plugs a little more securely to aid glueing them in. files updated accordingly.)

The switch is a 2 way on/on version so that i can wire it to switch from forward to reverse. Power in and out are the side holes and the reverse switch is on the lid. The front hole is for the potentiometer. (easily found on eBay)

The connectors have been in my workshop for ages but I think I got them from Banggood.

he On/On switch is a Miniature 6A 125V AC 6-Pin DPDT ON-ON Mini Flick Toggle Switch, also found on eBay.

Instructions on how to wire it can be found here:- https://www.instructables.com/id/Simple-Bi-directional-Switch/

Sorry, I cant seem to get thingiverse to show the STLs.

I have added another design to this. It includes a "buck converter" which can be adjusted to control the output voltage by the turn of a screw. this enables different types of motor bogies with different voltage needs to be catered for with the same controller.

It can be got as:- LM2596 DC to DC Buck Converter 3.0-40V to 1.5-35V Power Supply Step Down Module, from Amazon.

Another screen shot is included to show layout inside.