I liked the mount location of zadthebad's pi case, but it was just too many screws for me, so I added his bracket onto walter's sleve. Friction seems to hold the pi in just fine, even with the opening on the bottom - and if you need to remove it it's easy peasy.
I don't use the cap, but you can get it from the original if you'd like.
I've also added a 2nd version that adds a sleeve to hold a POE adapter that will let you power the Raspberry PI over POE. The adaper I use is at: https://www.amazon.com/gp/product/B01MDLUSE7 , but this seems to be a pretty standard size.