Rainward Sun

Backgammon, re-cut as a disc. The 24 points run outward from the middle like rays, the bar is a raised solar flare, and both armies are raindrops — one side forked at the tail, one side single.

Which means the sides are told apart by shape, not by colour. You can read the board from across a table, sort the pieces by feel in the cup, and print the whole game off one spool.

The Rainward Sun disc seen from above and to one side, drops set out in their opening lanes around a raised centre hub.
The opening position, solved from the board's own grooves and rendered from the shipping model.
35printed parts, nothing bought in
30drops, 15 to a side
24lanes, 6 to a quadrant
190 mmacross, 28 mm tall

A disc, not a box.

The board prints as one piece, 190 mm across the ray tips and 16 mm thick, with 16 rays standing proud of the rim. It does not fold and it has no hinge, so the whole game lives on one face.

Thirty drops find their lanes.

The lanes are grooves cut 0.6 mm into the face, 2 mm wide. Every 6 lanes one groove widens to 3 mm, and those four wide cuts are what make the disc read as four quadrants. The opening position is the one you already know, wrapped into a ring.

Forked, or single.

Here is the entire difference between the two armies. A fork-tail carries a notch 4 mm deep up its tail; a single-tail closes to a point. Both are 12 by 8 by 4 mm and sit identically in a lane — only the silhouette changes.

Two circuits, one ring.

Fork-tails run one way around the flare, single-tails the other, and the two streams cross at the wide quadrant grooves. On a folding board that crossing is a hinge you play over. Here it is simply the next lane.

A drop caught alone goes to the flare.

Land on a drop sitting by itself and it comes off its lane. It waits on the flare at the centre — a hub 48 mm across, standing 8 mm above the face, crested with a 4 mm plate — and re-enters the ring from there.

What comes off the printer.

The disc, 30 drops, two 16 mm dice you ink yourself, and two cups 42 mm across with a 38 mm bore. 35 parts, 6.5 oz of PETG, and no hardware at all.

Told apart by the tail.

A backgammon set normally asks you to tell dark from light. This one asks you to tell forked from single, which is a thing you can see across a table and feel blind in a cup. It also means both armies can come off the same spool — print a second colour if you want one, but the game does not need it.

Close view of two lanes meeting at the centre hub: the drops on the left taper to a point, the drops on the right carry a notch up the tail.
Two neighbouring lanes at the hub, either side of a wide quadrant groove. Single-tails on the left, fork-tails on the right — one filament, one light, and the sides still separate.

A lane is exactly five drops long.

Each groove runs 61 mm from the hub wall out to the rim, and a drop is 12 mm long. Five sit end to end with 1 mm to spare and finish flush at the rim. A sixth has to ride on top of the stack, so the lane itself shows you when a point is deeper than five.

61 mmgroove, hub wall to rim
12 mmdrop, nose to tail
5drops lie flat in a lane
0.6 mmgroove depth, one layer pass

Print it, or have it printed.

Printed parts
35
Filament
6.5 oz PETG
Print time
14.4 h over 2 plates
Disc alone
5.2 oz, 10.5 h
Drops, dice and cups
1.3 oz, 3.7 h
Size
11.1 × 8.6 × 1.1 in
Bed needed
200 mm square
Sliced at
0.2 mm layers, 15% infill
Ships within
14 days
Item
VB-DWY7RTK3

The listing carries the current price, the filament choices and the ship date. Buy it printed and it arrives boxed with the rules; the files stay yours to reprint under CC BY-NC-SA.

Every figure on this page was measured off the shipping model — the geometry, the slicer, or both. Nothing here is an estimate.