I first tried to find as many references that I could... which was not easy...
I saw pictures of cosplayers who have made, I re watched the anime, I tried fanart etc. and nothing helped me a lot... So in the end I decided to try to follow the image of the figure of Monokuma
With reference in hand, I drew each of the part separately
I made the base for the box with small pieces of wood and covered with eva foam and then painted the sides of red, leaving only the front white.
After accurately measure the front size of the box, I modified the side to get round and cut the center for the screen and put a piece of black eva foam.
Now on the black foam cut the center for the blue screen (I used blue fabric for this, but I forget to take a pic, sorry...)
put the fabric under the black foam
and then I cut the place for the buttons.
With insulating foam, cut the buttons and put in the box
For the red button
With a Styrofoam ball, remove the "cap" and give two coats of red paint and let dry~
To finish, cut some pieces of insulating foam, place together em glue under the red button.
Step 3: DONE!
Now you have a Monokuma's Execution Button for your Cosplay!
Oh look, you can press the button! V