I spent too much time looking for a solution that would work with any cell phone gimbal - a way to mount the GoPro session. I finally decided to make my own. The same mount will also work for other GoPro cameras - just mount with rubber bands. I've included two videos with this tutorial. One is an introduction with the original plastic mount, the other is a complete step by step tutorial on making the newer - and better - aluminum mount. Each video has sample footage shot with the gimbal at the end. This tutorial also covers the creation of the Aluminum mount - alternately you can follow the video.
Parts: 1.5" thin Aluminum flat stock, two pop-rivets.
Tools: Vice with non-mar faces, large needle-nose pliers, sandpaper, pop-rivet gun, large file. Drill and bit for the rivets.
Update: A added a counterweight arm to the mount! See the last step.
Step 1: Cut and Bend the Aluminum
Play it safe and cut it longer than you actually need - you can cut off the excess later. Cut the Aluminum however you want. I usually score and snap it.
The length of the Aluminum on the longer sections can differ with your gimbal. I make them too long to start and trim as needed. The offset also depends on your gimbal. You usually want the camera to be as close to the center as possible. You can make it deeper than needed and use self-sticking foam (the sheets are at Hobby Lobby for under a buck) to move it forward.
I clamp the stock in a clamp and just bend it manually - just make sure it's straight. If you use plastic - like I did in the first version - you can heat and bend it. With Acrylic you can cut and bond it. But the Aluminum is MUCE stronger and easy to work with.
Depending on your gimbal you may want to use counterweights with the final product. It reduces the strain on the motors.
Step 2: Make the Upright
The length of the upright depends on your gimbal clamp. It has to be long enough so the phone clamp grabs it. Each end should be folded over to create a rounded and smooth surface for the gimbal grip. I go into a lot of detail in the video if you need step by step instructions.
Step 3: Assemble and Test Fit, Cut the Slots for the Velcro Strap.
Next you need to center the upright and attach it to the bracket. Again, the video goes into a lot of detail. In short you want the bracket centered vertically but as close to the gimbal as possible. Mount the upright in the gimbal then dry fit and mark the position. Any excess can be cut and ground off after mounting.
This is also when you want to mark and cut the slots for the velcro strap.
Step 4: Cut Access Slots for Button(s) and Light(s), Finish.
The video has plenty of details. This bracket was made specifically made for the Session, so I cut an opening to access the menu button and drilled a hole to see the light. I used a file and extra fine sandpaper to clean all the edges, round everything off, and give the Aluminum a matte finish. A wire wheel works as well. I then washed the entire thing in Acetone and sealed with clear sealer.
You can compare the plastic to the aluminum versions in the photos and video. I use counterweights because it perfectly balances the camera. I have used this with three different gimbals. One needed no counterweight (but the gimbal could handle 400 grams), another needed two weights and another needed all four. So your mileage will vary.
Balance the camera the same way you would anything else with the gimbal. You can shave more weight off the mount. For example you can trim the angle off the bracket above the rivets and save 2 grams. Cutting an opening behind the camera can save 3 grams. But too many cuts will weaken the bracket. Heck, you can drill it full of holes and probably shave off 10 grams, especially in the doubled-up area by the rivets.
Also, you could add a bracket to the assembly that extends in the opposite direction from the camera and add weight to that as a counterweight. I'm going to experiment with that next.
Step 5: Optional: Counterweight Bracket
OK, I went overboard on this little piece. I could have simple made the bracket longer and added weight to that. But I wanted this to be easy to pack away, and this way it comes apart up for storage. I used 1/8" x 1/2" thick Aluminum stock. If you look at the photos you can see I used the existing rivets as stops and notched the end to it actually locks on a rivet. Since threads in Aluminum can strip easily, I wanted metal inserts. For the insert that attaches the weight support to the bracket I used a 1/4-20 insert and ground one end flat, plus ground the length down as needed so it was flush. I drilled the hole a little small and hammered in the insert. The support/threads for the counterweights is a threaded rivet - a really handy tool. I used 1/4-20" because I had some 1/4-20" threaded counterweights lying around. I NEVER throw away any old camera parts.
This is really secure and works great. For counterweights you can use nuts and bolts, fender washers, etc. In the past I simply would thread a bolt through the aluminum and attach nuts and washers to it as counterweights.
I added a video showing the mount in the gimbal.