This is a mount to hold a cell phone to your Syma transmitter. This allows you to use WIFI capable cameras as a FPV monitor. The cell mount is for a Samsung NOTE 3 in a case. I have also tried a NOTE 5 in a case. And while the NOTE 3 is a perfect fit--which it was designed for--the NOTE 5 in it's case fit with a little elbow grease. I did a little bit of "product testing" to make sure that A) the phone would not fall out and damage a phone that is more "valuable" than the drone (X8C). B) to make sure that if you grab the phone holder, it would not break away from the holder and drop your transmitter.
I think that this holder is pretty robust. You could almost say "chunky". With that said, if you don't have a NOTE 3 or are just unhappy with the design, I included the 123D Design file, so that you can modify the mount to your phone or your transmitter--if you are not using a Syma transmitter.
The phone weights almost as much as the entire transmitter, so the center of gravity of the transmitter is closer to the base of the antenna. So, I would HIGHLY recommend some type of lanyard. Also, if your case is not as exactly as wide as mine, you can use a rubber band to keep your phone from sliding out.
Speaking of phone mounts, I used tophe75's idea for a phone holder but not his file: http://www.thingiverse.com/thing:192129. I think his design uses too much plastic and would not work with my mount. If I had a different phone and more time, I would prefer a mount like this: http://www.thingiverse.com/thing:1133548
I will leave that up to the end user as I only have these 2 phones to try.
The design calls for either 5 3mm x 20mm Pan head/Cheese head machine screws or 5 #4-40 x .75" machine screws (also pan head/cheese head) and 5 matching nuts. With that said, I was able to use only 3 screw/nuts and it was more than strong enough. You can add the other 2 screw/nuts if your holder is not as tight. Also, I used captive screw holders that work for both #4 nuts and 3mm nuts. They are on both the top and bottom so you can have the screw heads point up or down--your choice.
As far as material and printing. I printed the two "Horse Shoe" pieces at .3 layer height and 50% infill with 3 shells. You want this piece to be VERY robust. The phone holder takes a lot more plastic and a .3 layer resolution and 10% infill is adequate. I would recommend 3 shells on this part, as the screw that holds this part to the "horse shoe" is transmitting all its retaining force through those 3 shells.
I printed a complete set in both PLA and ABS. I think the ABS is a better material for this application but the PLA held up fine. Since PLA is less flexible, the screw interface between the phone holder and the horse shoe mount will break and pull through with rough handling. For the record, both PLA mount and ABS mount were dropped--with NOTE 3 in holder-- and both held up.
Lastly, the phone holder could really use a sun shade. There are plenty of cell phone mounts on Thingiverse. You just need to make sure that is can be attached to the mount (16.5mm from edge to screw hold center on the mount). Again, the original 123D Design file is included so that you can make those changes for your phone if you do not have a NOTE series phone.
50% on transmitter mount /10% on phone holder
I printed in both PLA and ABS. ABS is a better choice for this project but if you don't have ABS, PLA will be fine.
Use 50% infill and 3 shells on the transmitter mount. You can always add more screws if you find something else you want to mount to your transmitter. 50% will give you something to drill through.
Use 10% infill and 3 shells for the phone mount.
You also need 5 machine screws and nuts. Either 3mm x 20mm or #4-40 x 3/4in pan head screws. Really, 3 is fine. The other 2 are for insurance purposes.
I also recommend sanding the two transmitter mount faces flat--the two that mount together. When the two halves are screws together, there should be no day light between them. My printing leaves a wavy surface that took two seconds to sand flat.