Update: I'm adding miniature voltage and amperage readouts soon. Just ordered them now and will include them in a newer build here. In total there will be 3 readouts, one for the outputs of both channels and the input channel. Should be added sometime next week as the meters won't arrive until Nov. 1st.
This is an enclosure I designed for making my own dew heater for my telescope. It has two channels with two RCA outputs on each channel and one input RCA jack which you can use whatever battery you want. I opted for a separate battery unit for easy swapping of batteries on the road. Find a battery that suits your needs, find an enclosure for it or make one, solder up an RCA connector, done. I ran the positive through the center pin of the RCA jack and ground is through the outer side but as long as you wire all your jacks the same it makes no difference. The PWM modules I used were rated up to 12V and 40A and I'll provide the links below.
The miscellaneous hardware was picked up from Home Depot along with the magnets. The rest was ordered online though ebay for pretty cheap. I used an assortment of M3 Nylon standoffs so the second PWM controller cleared the heatsinks of the first.
Print settings are pretty forgiving as I designed the box to be printed on it's sides meaning minimal supports. The only supports that need printed are for the back plate and the screw holes, the rest is flat so the external side of the box is nice and shiny for minimal to zero sanding. (I hate sanding)
The last part is a bit custom if you want, take a PWM controller and mount it in the bottom of the case. You can take some epoxy or superglue and glue the standoffs in to cut / sand off later for a cleaner finish. I opted to just use nylon nuts because I'm lazy.
As usual, I've provided all the SKP files for easy editing if you needed to change something up.
8x 3mm width by 8mm diameter neodymium magnets
12x 12mm or longer M3 screws
12x M3 nylon lock nuts
2x 12V PWM controller
5x Male RCA Plugs
5x Female RCA Panel/Chassis mount jacks
Preferrably black and red wire, any small amount will work
If you purchase the nylon standoff kit in the links all this is included.
4x 22mm M3 Nylon Standoffs
4x 10mm M3 Nylon Standoffs
4x 5mm M3 Nylon Standoffs
4x M3 x 6mm Nylon Screws
4x (Optional) 4-8x Nylon M3 Nuts
Just a heads up, if you decide to purchase the RCA Female Jacks from my list below, before putting them in remember to remove the nylon washers before installing them. The nylon washers prevent a connection from being made and you'll have created an open in the circuit.