Classical plywood and the modern Sugru product blend perfectly in the case offered by Instructables under the name Akron MakerSpace.
The master takes a sheet of pre-sanded plywood 5 mm thick remaining from the previous homemade:
He circles his smartphone, in this case HTC One M8. He makes the front panel, puts the perimeter of the display on it, cuts it out, processes it with a file:
Makes bottom with holes for rear camera, flash. Then adds the side walls.
Checks if everything went well by attaching the front panel. On the inner surface of the bottom, you can apply quite a bit of hot glue to press the smartphone to the front panel and prevent it from moving.
Cut holes in the front panel for dynamic heads, ear sensor, front camera. Makes openings in the side walls for access to controls and connectors. Marks where Sugru will be.
Now you can use the tool Sugru. Please note: on the one hand, it touches the front panel directly - there it will stick, and these will be flexible hinges for opening the cover. On the other hand, through an electrical tape, which will prevent sticking, and then it will be removed. These will be bendable latches that allow you to open the cover.
For some reason, the master decides not to show the result with the tape removed from the latches. But it is unlikely that he could not peel it off. And now at his disposal is a very convenient smartphone case made by do it yourself.