So, this door used to have a deadbolt.  But the bolt was removed and just sat their for years with an ugly hole. I took it upon myself to design a plug for it. About half way through the design i thought to myself, “Wouldn't it be cool if it had an old fashioned keyhole?”

The first problem is that doors come in different thicknesses. So in order for the keyhole to line up correctly on both sides of the door i either had to design the plug for a specific door thickness or i had to design it with an internal core that could be turned separately from the rest of the plug. Guess which option i chose lol.

This change in the design meant i was no longer half way through the design. Now i was maybe 10% through the design but it was a new challenge and i was excited.

I designed a custom thread profile for easy and reliable printing as well as guaranteeing the proper tolerance for the application. The question became, how to turn the internal core. And of course the answer was a key. I was already designing a key hole so why not a key too.

I ultimately made two keys. One can be used on the opposite side of the door to keep the key hole in the upright position. Otherwise it might shift a little during installation. I was able to install this by myself but without too much trouble but it would have been easier with a friend.

The one potential problem with this design is that the key hole of the core might not wind up perfectly aligned with the two outside keyholes. In my case they did but depending on door thickness you might not have the same result.