eBay has dirt cheap motor speed controls for sale,some are fairly heavy duty,I cant find a way to build them cheaper even with salvaged parts..the heater blower motor speed control is common in a lot of older cars,you know the simple 3 speed switch on the dash that controls the fan motor..getting a bit harder to find now due to the electronics doin it,but you can get them brand new replacement for pretty cheap too..just an idear for ya
