Fulcra · FL-2 · 83 pieces · Ages 8+
Push here. It lifts there.
$34.99
Fulcra is a hydraulic robotic arm you build from four sheets of laser-cut birch plywood and drive with water: eight needle-free water pistons on four color-coded lines move four joints.
1. Check the parts against the sheet map on page 2: sheet A, sheet B, sheet C, sheet D, 8 water pistons, 4 tubes, 8 clips, 24 pins, 12 rivets. 2. Pop parts out from the back with the pop-out pusher, never by bending; sand the tab stubs with the sanding stick. 3. Sitting 1, steps 1 to 24: base plate and turntable (sheet A), tower and shoulder (sheet B), boom, forearm and gripper (sheet C); press the snap rivets with a thumb and wipe the pivots with the wax stick. 4. Sitting 2, steps 25 to 40: the rack (sheet D); seat a piston in each rack slot and at each joint; route each tube on its marked side and close the clips. 5. Fill each line under the water: hook the tube end under the lip of the fill cup, draw the rack piston to its brim ring, tip the pair up and tap the air out, fit the joint piston with its plunger all the way in, then push the rack plunger all the way in; if the joint stops short there is air, so repeat. 6. Adult help recommended for the first build: steps 14 (tower rivets) and 31 to 34 (tubes onto the piston tips) carry a hand mark. 7. No screwdriver is needed; the pop-out pusher, sanding stick and wax stick go back in the box tray with the rack and the fill cup. 8. After play push the plungers in, wipe the arm and let the pistons and tubes dry in the tray.
Sheets: birch plywood, laser-cut, unfinished; A, B and D 3 mm, C 6 mm for the boom, forearm and gripper fingers; TSCA Title VI label on the box. Water pistons: polypropylene, needle-free slip tip, molded brim ring, silicone double-acting seal, no scale, no print; plunger and thumb-cap colored through, two per color. Tubes: tinted silicone, pigment in the compound. Pins: birch dowel. Rivets and clips: nylon, clips in one plain color. Pads: EVA foam. Grab-it pieces and pusher: solid beech, unfinished. Sanding stick: abrasive paper on a wooden stick. Wax stick: plain paraffin. Cup and timer: polypropylene. Box: printed board; molded pulp tray with a thin coating.
After play push the plungers in, wipe the arm and the rack, and let the pistons and tubes dry in the box tray. Tap water only: no soap, oil or other liquids. Wipe spills so the plywood stays flat; a damp sheet dries flat under the booklet. A wipe of the wax stick where wood slides on wood when a joint squeaks. Push the plungers slowly and lift with the arm, not by the gripper. Store with the lid on. A spare piston, a spare tube, four pins and four rivets are in the box; more spares in the Fulcra Spares pack; for a missing or broken part write to the address in the booklet.
WARNING: CHOKING HAZARD - Small parts. Not for children under 3 yrs. Keep small parts and packaging away from younger children and pets. Adult supervision recommended. Keep these instructions for future reference. Recommended for ages 8 years and up. Needle-free toy syringes. Not for medical use. Tap water only. No soap, oil or other liquids. Wipe up spills and dry the parts after play. Push the plungers slowly. Keep fingers out of the gripper and the joints while someone else is at the rack.
Fulcra · Arm + Challenge Set
Four joints, four colors, four pairs of water pistons. The same numbers are cut into the rack; the same drawing is inside the lid and in the booklet.
The control map
The sky line. The base turns 180 degrees on its turntable.
The poppy line. The shoulder raises the boom about 60 degrees.
The sun line. The elbow swings the forearm about 90 degrees; reach about 15 in (38 cm).
The violet line. Two fingers open to 2.5 in (6.4 cm); foam pads hold the ring.
Fill and bleed
About 2.2 fl oz (66 ml) of tap water fills all four lines. The box tray catches the drips.
The spares, up close
Pop parts out from the back with the pop-out pusher, never by bending; sand the tab stubs with the sanding stick.
A wipe of the wax stick where wood slides on wood when a joint squeaks.
A drip at a tip: push the tube on wet and straight, then clip it. A spare piston, a spare tube, four pins and four rivets are in the box.
At the kitchen table
The line
 Fulcra Arm |  Fulcra Arm + Challenge Set |  Fulcra Workshop | |
|---|---|---|---|
| Sheets | 4 (A to D) | 4 (A to D) | 6 (A to F) |
| Water pistons and lines | 8 and 4 | 8 and 4 | 12 and 6 |
| Spare pack | none | piston, tube, 4 pins, 4 rivets | piston, tube, 4 pins, 4 rivets |
| Fill cup | no (any cup) | yes | yes |
| Grab-it pieces and sand timer | none | 6 and 1 | 6 and 1 |
| Challenge cards | none | 10 | 10 |
| Map inside the lid | yes | yes | yes |
| Tray | plain | coated tray: holds the rack and the cup, catches drips | coated tray and a storage tray |
| Makes | the arm | the arm | the arm, an excavator or a scissor lift, one at a time |
| At the table | two sittings | two sittings | two sittings per machine |
Questions, care and the warning
Each rack slot is numbered 1 to 4 and colored: 1 sky turns the base, 2 poppy lifts the boom, 3 sun swings the forearm, 4 violet closes the gripper. The same numbers are on the sheets, and the same drawing is inside the box lid.
Under the water, to the brim ring. Hook the tube end under the cup's lip, draw the rack piston to its ring, tip the pair up and push the bubble out, then fit the joint piston with its plunger all the way in. Test on the table: push the rack plunger all the way in; if the joint stops short, there is still air, so repeat the second step. The booklet shows it in four pictures.
A drip at a tip means the tube is not on fully. Pull it off, wet the tip, push the tube on straight to the stop and close the clip. The box tray catches drips while you work.
Ages 8+. The build is two sittings: the base and the arm, then the pistons, tubes, fill and test. Adult help recommended for the first build: steps 14 and 31 to 34 (pressing rivets and fitting tubes) carry a hand mark.
The ring, the cube, the cylinder and an empty paper cup, yes; a clementine at mid-reach, yes; a full mug, no. It lifts more at mid-reach than at full reach, because the arm is a lever. Card 10 asks the builder to measure it: the kit's own cylinder on a kitchen scale, five tries, lines filled and bled, on a level table.
Tap water and a towel. No batteries, no glue, no screwdriver: the pusher, the sanding stick and the wax stick are in the box, and so is the fill cup.
No. They are needle-free water pistons made for the kit: 10 ml, a plain tip, a molded brim ring, no scale and no print, with colored plungers. Use them with tap water only.
The box holds a spare piston, a spare tube, four pins and four rivets. The parts under most strain, the boom and the gripper fingers, are cut from the 6 mm sheet. For anything else, write to the address in the booklet; the Fulcra Spares pack is sold separately.
3 mm and 6 mm birch plywood, laser-cut and unfinished; the box carries the TSCA Title VI label. Pop parts out from the back with the pusher, never by bending, and wipe spills so the sheets stay flat. About 94 pop-out parts on the four sheets; the 83 pieces in the box count each sheet once.
WARNING: CHOKING HAZARD - Small parts. Not for children under 3 yrs. Keep small parts and packaging away from younger children and pets. Adult supervision recommended. Keep these instructions for future reference. Recommended for ages 8 years and up. Needle-free toy syringes. Not for medical use. Tap water only. No soap, oil or other liquids. Wipe up spills and dry the parts after play. Push the plungers slowly. Keep fingers out of the gripper and the joints while someone else is at the rack.
Sheets: birch plywood, laser-cut, unfinished; A, B and D 3 mm, C 6 mm for the boom, forearm and gripper fingers; TSCA Title VI label on the box. Water pistons: polypropylene, needle-free slip tip, molded brim ring, silicone double-acting seal, no scale, no print; plunger and thumb-cap colored through, two per color. Tubes: tinted silicone, pigment in the compound. Pins: birch dowel. Rivets and clips: nylon, clips in one plain color. Pads: EVA foam. Grab-it pieces and pusher: solid beech, unfinished. Sanding stick: abrasive paper on a wooden stick. Wax stick: plain paraffin. Cup and timer: polypropylene. Box: printed board; molded pulp tray with a thin coating.
Concept project. Fictional brand, scenes visualized with AI. People in the photos are AI-generated.
About Fulcra
Fulcra began as a drawing: an arm with four joints, each one a pivot, each one pushed by water. We kept the drawing: its numbers are cut into the control rack, and the drawing is printed inside the lid, in the booklet and on every card, so a builder can look at the arm and at the drawing and see one thing. Then came a brim ring on every piston, a cup with a lip for filling under the water, a tray that catches drips, spares and a wax stick.