This was based on my 2016 WRX. It will probably fit the entire 2015-2018 WRX generation, including the STI. Might also fit other late model Subaru vehicles that might utilize the same trunk latch.
I will find out what size bolts are needed and put it here later... M5 or M6 (from memory) maybe. Socket cap bolt. Just at 10mm to the length. There are inset areas on the ends for washers. Again, I'll double check and have the info here later.
I've printed at 0.2 and 0.3 resolution. I think 0.3 gives a rougher feel when using the handle, which I like.
I give it infill because there's a torque against it when you pull on in.
ABS or Nylon.. something that has a higher glazing point is ideal for this since it's potentially in high heat.
However mine is currently in PLA and it's been fine for 2 years. (I'll be replacing it with a nylon one when my nylon filament arrives, just to comparison test)
Remove the two bolts that hold the trunk latch in place.
Hold the trunk latch and it's plastic cover in place and, with the washers in place on the ends, slide the legs of the printed handle into the bolt recesses of the plastic cover.
Insert the new socket cap bolts and hand tighten.
Do NOT over tighten the bolts. Over tightening the bolts can cause the latch mechanism to fail to release once the trunk is closed.
If this happens, you have to crawl through the back seat into the trunk to pull the release. If you have kids, have one of them do this.
I have had my original print of this handle on my car for nearly 2 years (through 2 summers and 2 winters). I have not had to tighten it since the day I installed it. It's still quite snug.