Bryan, here you go.
Alpha 100K Linear slide potentiometer
Slider knob for above.
DPDT Centre Off Switch
Case to house it in?
Remount LED on case?
View attachment 231428
DC Speed Controller board, picture below shows both types in use,
The smaller one:
Specification: Input voltage: DC6V - 28V Sustained current: 3A PWM duty cycle: 5% - 100% PWM frequency: 21KHz
And the one previously referred to:
Specification: Input voltage: DC12V - 36V Sustained current: 3A, Max. 6A PWM Duty Cycle:0 -100% PWM Frequency:500KHz
View attachment 231430
Just waiting for the cases then these can be assembled.
As for their sustainability and performance, two have been in permanent use for over three months, a third for the automatic shuttle was added for the Christmas Fair exhibition, all three were in operation for the two days, and they got hammered, by both young and old visitors, plus the operators gave the entire loco fleet a good workout!
Two more were assigned to the shop window display for automatic shuttles, this pair are about to enter their third week of 24/7 operation.
Meters, prefer these types, variety of AMP and Voltage levels available.
View attachment 231431
evilBay is useful and probably convenient for searching and tracking down the bits, there are other places to obtain the items.