Hi,
First of all i am a complete noob regarding building things..
(my next project will be foam )
i made an mechanical arm from cardboard,duktape some paint and an old sword from my kids
I first made cardboard arm from instructions from this video:
https://www.youtube.com/watch?v=PqOetlij6G4 i was pleased by the results looking like :

so i made another one now with ductape because i had to wear it outside and was afraid of rain .. :

Painted it a little bit with a sponge for metallic rust look, added some deatails and it turned out like :

i guess u can change the cardboard for other materials to make a stronger product