This 3D printed battery connector is for a very common cheap power tool battery sold in Europe.
It goes by the brand Parkside Tools here and is sold by Lidl. It may be available in some countries under a different brand.
There are quite a lot of battery connector designs on Thingiverse, but they all seemed quite complicated. So I decided to make a very minimalist one that prints fast (12 minutes), fits snugly and just does the job.
You can find a longer video showing the gluing process here:-
https://www.youtube.com/watch?v=0oBbF3bcDck
Note that some battery packs do not have internal overdischarge protection, so care should be taken to avoid discharging the packs below around 3V per cell. For an 18/20V pack that's usually around 15V. The connection system is actually pretty solid, so with good quality plated copper spade crimps it should handle a decent amount of current, but don't push it too far. I'd envisage this adaptor being used for things like lights and USB chargers. Adding an inline fuse is always a good idea.
Here's the openscad script. Just copy and paste the text below into the openscad freeware and then build and save the STL file. I'm doing it as a script so you can hack it to fit other battery systems.
//Parkside battery mini adaptor
//Use with two male spade crimps
difference(){
union(){
//main block
cube([46,20,10]);
}
//side slides
translate([-1,5,5])
cube([6,21,6]);
translate([41,5,5])
cube([6,21,6]);
translate([4,5,-1])
cube([3.5,20,12]);
translate([38.5,5,-1])
cube([3.5,20,12]);
//Terminal cutouts
translate([8.5,1,1])
cube([6,18,10]);
translate([31.5,1,1])
cube([6,18,10]);
//terminal slots
translate([10.5,17,1])
cube([2,10,10]);
translate([33.5,17,1])
cube([2,10,10]);
//cable slots
translate([10,-1,4])
cube([3,10,10]);
translate([33,-1,4])
cube([3,10,10]);
//plastic and time saver
translate([15.5,1,1])
cube([15,18,10]);
}