I came across this neat little tool/toy on Kickstarter: https://www.kickstarter.com/projects/699604098/gravity-hook-a-high-performance-grappling-hook/description
My effort in showing it here is not to steal their idea but to expand on it(Yes, I am a backer of them today for their new keychain version). 
QUAD COPTER USE: I can see all sorts of little retrieving claws from quad copters… what if that was a Oculus rift game? To see who could retrieve the most objects in a race. Or what if they were actually used for a reason? Like to explode mines or to deliver or retrieve medical items in a hot zone?
ROBOT USE: Or little plastic robots that use the hinge technique to move their legs. All you would need is a arduino and some servos. There once was this little wooden desk toy I saw:
I saw a larger version where the inventor Theo Jansen let it wander a beach.
Strandbeest is the robot thing. How does that tie in with the hook?
Just, in my mind, how the legs of the robot look like the joints of the claw. It is the same use of materials, just arranged differently.
That’s a cool idea. What material would you use to make your own?
Honestly, (though I know I would have to get it sent away to be cut by a bigger machine.) I would love to have it cut out of Damascus steel Billets
. I love Damascus steel because of a necklace I made out of a Damascus steel arrow head 15 years ago and it still looks awesome today (
http://www.by-the-sword.com/p-3056-damascus-arrowhead-broadhead-db-2214.aspx) Thanks for asking Polarbrainfreeze! What would you make it out of?
I’m not sure what we could cut with the GF that would be strong enough.
I guess I’d try it with 1/4 acrylic or MDF, and then test it out for strength. It would surely not be as strong, but on the other hand, it may be less dangerous than steel for the kids to play with. I think they would love a “grappling hook” in their tree house.
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Yes, you are right, acrylic would be the easy option to choose. If I was going the non metal way… perhaps a plastic I would choose Polycarbonate Sheets to use(Like Police shields). I read up on Delrin and it seems to produce harmful cancerous vapors when burned. Here is a cool page I found on plastic hardness in sheets. I am basically thinking in terms of, if I am going to make something I don’t really ever want it to break.
http://plasticmentor.com/361/is-polycarbonate-sheet-the-strongest-plastic-in-sheets/
I see how the profile of some pieces are similar. But the big thing about strandbeests in the Jansen’s Linkage, which allows them to use simple rotary motion to move like a natural limb/stride. I might be seeing things wrong, but the grapple appears not to be articulated at all.
To improve on the design for the grapple, I would look for a way to make it collapse to a flat object and re-assemble easily. Makes transport/storage nicer. That accomplished, I would then look for a way to make it re-assemble from flat automatically, with the motion of retracting the rope. Then you could throw out a flat object (better profile for distance), and when it passes your hook target, jerk the rope and Snap, your hook assembles and latches on.
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