I created this to support the popular Samyang (Pro-Optic etc.) 8mm lens and use it to create spherical panoramas (AKA 360x180 or Equirectangular). I use a Nikon D7000 body, but this mount will accommodate other DSLR bodies. The head of the mount has detents to allow you to easily align the camera (in portrait mode) horizontally (for standard panoramas), -15 degrees and +60 degrees. To create a spherical image, take 6 photos (60 degrees apart) with the camera pointed at -15 degrees and two photos pointed at +60 degrees (180 degrees apart of course). Longer lenses will require more photos so do a little research if you're using something other than the Samyang 8mm lens. You can deal with the small gap under the tripod with photoshop or an image taken hand held (good luck with that). There are many tutorials on the web detailing the process to create the spherical image from these 8 (or 9) photos. I use the open source software Hugin, but there are other solutions.
For initial setup, measure the distance from the bottom of your camera to the center of the lens and secure the vertical arm so the center of the lens is in line with the center of the tripod mount. On the horizontal arm, where the camera is mounted, mount the camera so the lens nodal point is in line with the pivot point. For the Samyang lens, this seems to be at the gold ring that's near the end of the lens.
My printer bed is not big enough to print the vertical arm and the very small part that aligns the arm with the base so I split it off. The alignment pin is designed to be attached to the bottom part of the vertical arm with glue and a couple of small screws. I used 1/4-20 bolts and nuts to attach the vertical arm to the base, the vertical arm to the horizontal arm, and camera to the horizontal arm. I had on hand a knob with an embedded 1/4-20 threaded rod, but you could also use a bolt and wing nut.
As you can see from the photo, there is an inset for a common bubble level. The diameter of the level is 43mm. (example https://wholesaler.alibaba.com/product-detail/bubble-level-vials_60291126290.html)
See some of my panoramas at https://www.360cities.net/search?utf8=%E2%9C%93&query=wt4y and https://www.flickr.com/photos/wt4y