12 February 2017
I made a thing. Here's how I made this thing using 3D printing.
Raspberry PI $33.68 (Probably overkill, but the servo I bought required 5V)
3D printed a model $37.21 (Had to print two revisions)
Price range of smart locks these days: 100-300
*Disclaimer: This solution doesn't have the same features as the smart locks on the market these days and definitely doesn't look as nice.
So the door we have is a weird shape and because we're renting, we didn't want to modify it too much, so we decided to create something that replaces the plate and knob which turns the deadbolt. Then using a caliper, we determined the dimensions of the plate.
I used FreeCAD to convert those dimensions into a 3D model. There was a learning curve, but I was able to go from no 3D modeling experience to this in just a few hours, so it's doable.
So then I got it printed using Hubs for about $20. I don't know if that's the best site, or whether I payed too much, but it worked for me. Now this first revision didn't work and actually broke because the first revision wasn't designed very well.
I went back to the drawing board and came up with a second revision which addressed the concerns of the first. Fortunately for me, all I needed was a second revision. There are areas where I could improve, but for all intents and purposes, this one does what I want.
I then followed this tutorial to hook the servo up to the Raspberry PI and create a simple python script to control it.