I have an old Jeep Wrangler which also has a viper alarm/remote start installed. The key fob for the remote start broke off of my keyring a while ago and I always seem to misplace it. Today I decided to design and print a snug holder for the key fob and it turned out pretty good on my first try.
I also came up with a pretty handy way to design the case to fit the curves of the remote without having to do a lot of measuring.
I ended up designing this piece for the viper remote model RPN 7142V using my cellphone camera, adobe illustrator (Inkscape would work also), and Google Sketchup.
You can download and print this design for free from Thingiverse here http://www.thingiverse.com/thing:1987932
The whole process from design to print took about 1.5 hours. Here are the steps I took to create it:
The first thing we need to do is take a 90° photo of the key fob to capture all of the curves in the profile.
I used Adobe Illustrator for this step since that’s what I’m familiar with, however Inkscape should work as well. The trick here is to use the pen tool to create an outline that perfectly (close as possible) matches the outline of the key fob. This step keeps you from having to measure every single curve in the part by hand.
Once you have the profile fully outlined you can export the shape as an autocad DWG drawing by going to file using file>export>DWG. This will allow you to import the shape into Google Sketchup. Also, the line going down the middle of my shape is something I did since my fob is symmetrical and my hand drawing wasn’t. What I decided to do was draw the curve really well on one side then reflect it over to the other so it would be a perfect fit. There may be a better way to do that in illustrator but this got the job done lol.
Once you import your shape you can see that it’s just the outline. You can fix that by adding in the sketch extenuation “Make Faces” which will fill in any selected paths that makes up a complete polygon.
Since your sketchup shape is the exact (close to) profile of your fob all you have to do now is measure one cross section of the device with a caliper and match the demission within sketchup and all of the other demission should fall in place. For this you have to use the scale tool, select the shape and hold down shift or command (on a Mac) when scaling to make sure you keep your aspect ratio and nothing gets warped. You’ll see the demission dynamically change as you scale the image. Using this method you can literally make one good measurement of the largest cross-section to get a good profile of your device, if you traced it well in illustrator. I just made the bottom plate extrusion 3mm so it’s not to bulky yet sturdy.
Step 6: Add supports and other features
Now that you have the main shape with a near perfect measurement all thats left to do is add some supports, extrude a hole for a key ring and print. You can get as fancy as you want here however you may want to take more measurements to make sure you have the height correct for the supports and make sure you have enough support so your fob doesn’t fall out.
Let me know if you found this method helpful or if you have an easier way of making cases for curved parts by dropping a comment below.