• Round Dice, a perfectly round white six-sided die, on a wooden table
  • Cutaway of the round die showing the hollow shell and the loose inner ball
  • Round Dice in three sizes: 38, 55 and 70 mm
  • Results of 1,000 test rolls: 154, 181, 178, 149, 162, 176
  • Round die held between finger and thumb
  • Round die resting on concrete
  • Round Dice rolling and settling on a number
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PYG — Original design object

Round Dice

Round Dice

$22.00 USD
$22.00 USD
Sale Gone. For now.

A perfectly round die that keeps rolling like a roulette wheel, then lands on a number. Fair, tested, and very satisfying.

Size

Most dice clatter to a stop in two seconds. This one keeps spinning and spinning while everyone watches, then settles on a number.

How it works: the die is a hollow ball with a loose ball inside. The inside wall has hills and valleys. Wherever there's a number, there's a valley, so the inner ball can't stop on a hill. It rolls into the valley under a number, and the number on the opposite side points up.

Fair, not just round. I tuned the inside shape in a physics simulator over thousands of throws so no number is favoured, then tested the real die with 1,000 rolls: 1: 154 · 2: 181 · 3: 178 · 4: 149 · 5: 162 · 6: 176. That's what a fair die looks like.

Printed in one piece in white SLS nylon, ball and all, so there's no seam to weaken it. The pips are real holes. The surface has a fine, slightly grainy matte texture from the printing process, and it feels a little chalky at first. That wears off.

Pick tiny numbers on a big die, or the other way round. All three sizes roll the same way.

Specs

  • Sizes: 38 mm (about 15 g), 55 mm (about 45 g), 70 mm (about 93 g)
  • Material: SLS nylon (PA12), white, one piece with a captive inner ball
  • Made to order. Ships within 4 weeks.
  • Returns accepted within 2 weeks of delivery.

Good to know

  • Roll it on a level surface. A sloped table will bias any round die.
  • Hard tables and felt both work well. Very soft mats slow it down.
  • A little powder may still come out of the holes at first. Shake it out or blow through the pips.

FAQ

Is it actually fair? Yes. It was tuned in simulation and tested with 1,000 real rolls (above).

Why does it roll so long? There are no edges or corners to stop it, so only the inner ball slows it down.

Can I print my own? Yes: the print files are on my Patreon: patreon.com/c/pygmallionaire

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