I don’t claim to be a good 3D designer, or CAD artist - so keep that in mind. Remember it is provided for free, and sometimes you get what you pay for. 
I wanted a compact case to use with the RAK19003 base, so I designed one. Feel free to use/change/extend/improve as you see fit. The design includes room to put a 102535 battery next to the board. I picked that battery as a compromise between capacity (I use 1000mAh 102535) and space required. It being a similar shape and thickness to the base made the design easier as well.
There are three different body designs depending on sensor configuration.
I could have made it probably 3mm shallower if the battery connector didn’t stick up so high. I guess I could have unsoldered the jst connector and resoldered wires directly to the board, but I am trying to save time.
Side note, the new power modules don’t help too much in this regard either.
RAK19012 is the same - vertical connectors.
RAK19015 is horizontal (saving vertical room), but the plug extends out past the edge of the board, meaning you still have to add extra space to a case to fit the battery connector. I wish they would have rotated the battery connector 90 or 180 degrees so that it went over the power module/base instead of off the edge…