Volvo Sport Key Replacement Case

Update: 01/03/2024: Added a slot to help with opening the cap on the V2 model.  If printing in FLEX it isn't as big a deal but if printing in a more rigid material it can be difficult to take the cap on and off.  You may want to file down the inner ridges to help with this.

Update: 08/11/2023: There is a new version (signified by V2 in the stls) that is a smaller design and caps from the battery side to make changing the battery easier.  I recommend printing it in FLEX to avoid noisy keys.

The Volvo Sport Key is a great idea in that it provides a small form factor key fob that is waterproof, something you can take with you in the pool, surfing, etc.  It's also great for everyday carry as it doesn't take up too much room in your pocket.  The only problem is that the CR2032 battery only lasts a couple of years.  The Volvo dealership will be happy to replace it for several hundreds of dollars!  This case allows you to have something to hold the circuitry in after you've extracted it from the original case.  It is NOT waterproof but it is still significantly smaller than the regular key fob.

Use a Dremel to cut the sides of the original sport key.  You don't have to go very deep, just enough to be able to pry it apart.  The dead CR2032 battery is soldered directly to the board.  Simply pull it off of the solder pads.  I ended up getting a 10 pack of Coin Cell Button Battery Holders for CR2032 from Amazon (~$5).  Use some spare wire to solder the leads from the battery holder to the appropriate solder pad (see attached for polarity).  I used double-sided Scotch tape to hold it in place (chosen for its low profile, it seems to be sturdy enough).  

The top snaps into the bottom and is a TIGHT fit.  Hope your printer is well calibrated as I only added in the smallest of margin.  I printed it at 0.15 and it turned out awesome.