The arms looked "Butch" to most people I've shown them to, so it was time to slim them down. Since it's not easy for her to go on a diet , like most Americans , we resort to massive cosmetic surgery! I'll be showing the steps to make an entire set of arms, which can be adapted to make all sorts of other parts.
First , you'll need to design some parts. To make a hinge joint that allows for axial rotation, you'll need three parts: one for the male end (in this case, the elbow joint) and two for the female end (the arm connector bit things). From the small , mildly blurry pic, you can see a pink thing with three elements removed. From left to right, we have the elbow piece, the outer housing (with an extra stick thing that I accidentally put there) and the inner housing with a stick coming out of it. This pink thing is my makeshift tracing template. You'll need some of the following materials shown before you proceed:
A stylus (mine's real bootleg, being a tack taped onto an X-acto knife shaft)
Some binder clips (to hold the parts together as they dry)
Scissors, and a 1/8" hole punch (not pictured)
Chaff Magic the Gathering cards (to sacrifice for the greater glory of YAWGMOTH!) You can see here I've chosen a Giant Octopus with proxy text scribbled over it. You might have to resort to more delicious offerings like crap rares if you want to go for style, or with a crapload of plains. I like using stuff from a pile of reject cards I personally hate.Side note: make your shafts 3mm in width. You'll need them to fit snugly into a custom tube.
Now that you have everything, trace 8x of each part with the stylus onto the MtG card. After developing carpal tunnel, cut out these pieces as best as you can. You might notice the scattered assortment of bits with holes in them. You'll need to make holes in with the 1/8" hole punch to allow for the bolts to go through. Since I designed my hinge joints around 10mm diameter circles, I naturally put the hole in the center. If you like hobbled figures, put the hole off center or at a bad place. However, I personally like having figures that aren't eligible for disability checks.
Here's a completed elbow piece. This piece will support two arm attachment points to allow for more movement. This was built from laminating 8x layers with Elmer's glue and allowing it to be clamped dry with binder clips.
Behold the magic cube! This is a 12mm cube I built specially for the next set of construction processes. It has a 1/4" hole in two ends, to allow for threading a hollow tube 6.35mm in diameter to be inserted. You'll preferably want one of these made for this purpose. This one uses 4x layers to stiffen it.
Now, a 17.5mm long piece of card was rolled and inserted. I made mine 12mm long to accommodate for two shafts to be inserted. You can ignore that and make yours long enough to be supported by the magic cube.
After putting in your makeshift cylinder, roll up some 110mb cardstock 37mm long into a hollow tube and somehow stick it in there. I like to partially insert it, put glue around the base, then shove it in to allow the glue to spread inside.
This is the finished female arm joint. Note the stick coming out. That is going to have to fit tightly into the tube.
Insert like so.
Here is the finished joint, composed of two female ends onto the B shaped elbow piece. I have used some small bolts and nuts to secure it. Naturally, I added some washers to help reduce wear and increase grip.
"Dear me, this isn't going to cut it for a new arm. I demand you finish the rest of it!" -Hotaru
In order to complete the arm, you'll need to wrap another card around the newly made cylindrical stubs to make a tube that will tightly fit it. Secure this larger tube to one of the smaller tubes (I cut some notches in one end to overlap the arm assembly bit) and glue. With the other end, you can now insert another similarly shaped tube made with the magic cube into it to make a force fit rotation joint. Now you have a hinge joint that can rotate to provide more movement. I've fitted some extra elements onto mine, namely cone frustums to flesh out the arms to make them more round. I'll detail how to make those later.
This is the arm after cosmetic coverings were added. Here, you can see 1/4" hole punch scraps used to cover the nuts. I've added epoxy to the nuts to prohibit movement before covering them, so I'll never have to worry about them slipping as I adjust the screws on the other side. The arms are now ready for sanding and painting.