These are several options for a top plate replacement for the TransTec Frog. I've been running TPU top plates for a year now, and they are very durable and versatile. I've been racing with the shark fin, but recently wanted to use my GoPro on my Frog frame, so I created the file. I usually fly with a 40-45 degree uptilt, but my friend usually flies with 25, so I made both. The GoPro fits very snugly, and shouldn't need any additional traps to hold it in while flying.
Basic top plate with options to add camera protection or ridges for rigidity
Top plate with a shark fin, with and without a place for an AXII or Lollipop antenna
Top plate targeted for 25 or 40 degrees of uptilt, with options for GoPro mount and/or AXII/Lollipop mount
If you measure the tilt of the mounts in the STL files, you'll see that they are 10 degrees less than specified. That's because the top plate on the Frog is already tilted at about 10 degrees with respect to the flight controller.
3 perimeter walls should be your minimum, 4 or 5 would be even better for a high strength print.
TPU will give you the best strength for a long lived part. All my racing quadcopters now use TPU top plates with fins.
If you want a rigid top plate, PETG or ABS will give you better strength and better heat tolerance than PLA, but PLA will work fine too.