Studio Secrets: DIY Ball Joint Kit (Steel Balls, Brass Plates, Screws, Wing Nuts)

Ships in 1–2 weeks. We put each kit together by hand when you order.

Why we made this: back in animation school, our founder spent about $120 on a store-bought armature that turned out way too big for his puppet. This is the kit he wishes he'd had: build your joints to exactly the size your character needs, for a fraction of the price.

What it's for: making your own ball-and-socket joints, the kind pro armatures use, without paying kit prices. A ball-and-socket joint holds a pose better than wire and never fatigues. You can tighten it as it wears, so a puppet built with these lasts through a whole film. This is the double-plate "sandwich" joint animators have hand-built for decades.

What's in the box

• 20 hardened 1/4" steel balls
• K&S brass strip (.032" x 1/4"), for cutting into joint plates
• Machine screws and wing nuts, one set per joint
• A build card with drilling measurements

How the sandwich joint works

1. Cut two matching brass plates. Clamp them together and drill a hole near each end that's a little smaller than the ball, so each ball seats in the hole like an eye in a socket.
2. Drill a screw hole in the middle, between the two ball holes.
3. Sandwich a ball in each end between the plates, run the screw through the middle, and snug the wing nut. Tighten for a stiff joint, and loosen for a free one.
4. Bond each ball to its "bone" (brass tube, wire, or threaded rod) with J-B Weld or epoxy putty.

Studio secrets

• Don't drill the balls. Bearing balls are hardened steel and will destroy a drill bit. The plates do the gripping, and the bones get bonded on.
• Size it to the puppet. Cut the plates shorter for a small puppet's fingers and neck, and longer for the hips. That's the whole advantage over a one-size kit.
• Stiffness is adjustable. Hips and knees need to hold the puppet's weight, so run them tight. Wrists and the neck can run looser for fine moves.
• Add a drop of blue thread-locker (Loctite 242) once the tension is right, so joints don't creep loose mid-shot.
• Want them ready-made instead? See our CineSpark ball-and-socket armature kits.

Needs a drill and a small file. Not for children under 14: small parts.