I found it was a lot easier to find lone controllers than it was to find the docks; and many of the existing docks are either dead or dying. It's a very simple device so perfect for 3d printing.

You'll need a few extra parts to assemble this:

1. A pair of pogo pins. I used 7.5mm long pogos with a 2.5mm body width, which gives a decent friction fit that helps setting them before you glue. Smaller is fine, you'll just have to be a bit careful when setting the depth. The ones I used can be found here (I cut them into singles with a pair of edge cutters) but you can probably find a better deal. https://www.amazon.com/dp/B09NKF2Y5S

2. A USB to 5v adapter. There are tons of these floating around, so just pick one that looks about the right size and make sure it puts out 5v, not one of the higher PD voltages. I used this model, but be ware you need to modify the jumpers to get them to output 5v, you can probably find a better deal elsewhere on a 5v only model. https://www.amazon.com/dp/B0DBPP52FD?th=1

3. Some glue to permanently fix the pins into place. I just used hot glue, but any high fill glue should work (epoxy, etc). You don't need much strength to hold the pins in place.

4. Some wire if your USB adapter doesn't come with wire tails pre-soldered

5. A soldering iron and some solder.

Installation is fairly straightforward. Make sure you get the polarity right. With the dock facing you, positive is on the right side, negative is on the left (eg, positive is on the "next" button side). Solder the usb adapter to the non-pogo sides of the pin then insert the pin into the hole. 

I installed the pins past max depth, then used the remote to push them down to the correct depth (eg, push the pins in a bit too far, then push the remote into the dock until it bottoms out. Fix any pins that might have rotated, then repeat until you get a good seat.) There should be enough friction to get them to sit fully retracted using this method.

Once you're happy with the pin position, glue them in place and enjoy. Some USB cables may stick out further than the bottom of the dock, so you may want to use some rubber feet on the bottom to both give it a bit more height off the table, and also help prevent it from sliding around.

I've included the step file as well if anyone needs it. Sorry for the bad example print, it's way too cold out right now to sand and paint anything, and PLA is fighting me with the printer in my 5C garage.