It's boondongles, from his gallery. He put it up two years ago, so the regulator is most likely a 3-pin from
madvapes and the connector looks homemade, a hex nut or something. The one they carry now that has
threading and a nut would be helpful for this.
The switch I don't know, but it sounds like the one you have from RS is really close if not the same. It is the bottom of the battery box where the master switch goes, so there is less depth for the connector, and the negative pin from the regulator is soldered directly to the battery tab and there is probably some black wire in there too that doesn't show up in the picture well.
If the screw post was removed it wouldn't be so cramped, but then closing it would be more difficult to achieve. Maybe a magnet glued to the lid that sticks to the magnets?