Nine modules, eight joins.
Every module is a piece of ridge with a length of wall over it. Seven carry the wall through; two are gate towers, where it starts and where it stops.
Ridgeline
Nine mountains, and one wall that has to cross every one of them without a break.
Nine printed modules drop into a numbered tray. Each carries a length of Great Wall that opens on two of its four sides — one, if it is a gate tower. Turn them a quarter at a time until the wall runs unbroken from the brick tower G1 to the teal tower G2, matching both the heading and the height at all 8 joins.
9modules in a 3 × 3 tray
14challenge setups
12 mmbetween one wall height and the next
8joins to get right at once
Take the board apart.
Every space has a number.
Lift the modules out and the tray reads 0 to 8, left to right and top to bottom, with the north tab pointing away from you. Every challenge diagram uses those same numbers.
Turn it, never flip it.
A module has 4 positions and you reach them a quarter turn at a time, lifted clear of its neighbours. T reads the same after a half turn; S and U have ends at different heights, so reversing either one changes the puzzle.
Match the heading.
Two openings have to face each other across the 0.4 mm seam. Every opening on every module is the same 21 mm wide, which makes direction the easy half of the test.
A join is only half the test.
Reverse S and the wall still points the right way — but its low end and its middle end have swapped, and the crest now steps by 12 mm. Turn it back and the two walls run level.
One walk, G1 to G2.
8 joins, nine modules, no loose ends and no separate loops. This answer runs 6, 7, 8, 5, 2, 1, 0, 3, 4 — out along the south rim, up the east side, back along the north, then in to the tower at the centre.
Know your wall.
One each of A, B, C, D, S, T, U, G1 and G2. The discs on each card give the heights of that module's open ends — 0 low, 1 middle, 2 high. Match the discs and you match the crest.
Acorner
10
Turns a corner and steps down onto the low terrace.
sandstone
Bcorner
11
A corner that stays at middle height the whole way across.
sandstone
Ccorner
12
Climbs from middle to high as it turns.
sandstone
Dcorner
21
The other middle-to-high corner. Its high end sits on the opposite side of the turn from C's, and no quarter turn will swap them.
light sand
Sstraight
01
Straight through, low at one end and middle at the other. Reversing it is the classic mistake.
moss
Tstraight
11
Straight and level. A half turn gives you the same module back, so it really has two positions.
deep moss
Ustraight
12
Straight, with the climb from middle to high taken inside the module.
dark moss
G1gate tower
1
One opening only, at middle height. Every walk starts here.
brick red
G2gate tower
2
One opening, at high. The tallest module at 59 mm, and where every walk ends.
teal
Each module is 55.6 mm square and drops into a 56 mm cell, so there is 0.4 mm of air at every seam — enough to lift one out and turn it without disturbing its neighbours.
Direction is the easy half.
Wall heights come in 3 — low, middle and high, 12 mm apart. Two openings can face each other perfectly and still be wrong, which is what makes a board full of matching joins worth checking twice.
The whole answer in section: the walk from G1 to G2 across the 3 heights, with a disc on each of the 8 joins.
Fourteen setups, one answer each.
A challenge fixes a few modules as clues and leaves the rest blank. Fill every space, use each module once, and let no wall end point off the edge of the cradle. Separate loops do not count — the walk has to visit all nine.
Counted over the whole set there are 56 complete answers. Treat a quarter turn of the whole board as the same answer and they collapse to 14, one for each challenge. Those 14 trace only 4 shapes; reading each from G1 towards G2 separates 6.
- 14
- setups, starting with a guided two-module opener
- 56
- complete oriented answers across the set
- 4
- distinct route shapes on the board
- 13
- pages of guide, answers kept in their own section
Ten printed parts, nothing else.
Nine modules and the cradle. Nothing is glued, clipped or screwed. The engraved grid guides placement without locking a module down, and 4 finger notches 30 mm wide are cut into the rim so a corner module lifts out cleanly.
- Assembled
- 6.9 × 7.2 × 2.5 in, north tab included
- Cradle
- 174 × 174 mm body, 5.5 mm high on a 4 mm floor
- Engraving
- grid and numbers recessed 0.6 mm, leaving 3.4 mm of floor
- Module
- 55.6 mm square on a 56 mm pitch
- Heights
- 3 levels 12 mm apart, openings 21 mm wide
- On the plate
- 9.5 oz and about 21.0 h for the set, sliced at 0.2 mm with 15% infill and 2 perimeters
- Bed
- 182 mm minimum, set by the cradle
- In the box
- 10 parts, editable Python, coloured STEP and a 13-page guide
This is a digital prototype. The geometry is checked in CAD — the engraved marks, the floor left under them and the absence of any module-to-cradle overlap — but it has not yet been printed, fitted or played.
