Play Date Calendar Cube transforms the familiar perpetual calendar into a playful daily ritual. Designed by Sean Dempsey, the interactive calendar uses the mechanics of a classic puzzle cube to let you twist and turn your way to each new date.
With all 365 days cleverly hidden within its six faces, Play Date offers a quick, satisfying daily solve before sliding softly back into its wooden case to display the date for the rest of the day.
ABOUT THE DESIGNER
Sean Dempsey is an industrial designer, inventor, entrepreneur, and dad. He is drawn to clever, deliberate design—products that feel simple, intuitive, and a little bit magical. As Design Partner at Charlie Ray Design, he develops thoughtful consumer products across diverse categories including toys, games, sporting goods, housewares, and outdoor furniture.
DESIGN INSPIRATION
The idea for Play Date began with two interests: puzzle cubes and daily word games.
When he was younger, Sean’s son Fraser became interested in speed cubing and taught Sean the basic algorithm to solve a Rubik’s Cube. Having played with one as a child but never learned to solve all six sides, Sean became fascinated by the mechanics of the cube and began exploring his own variations.
At the same time, games like Wordle and Connections had become part of his morning routine.
“I loved the idea of having one small puzzle to solve every day, but I wanted to explore what that experience could be mechanically instead of on a smartphone.”
The connection to a perpetual calendar came naturally. Sean remembered the bank branch calendars he had seen as a child, where the day, month and date were manually changed each morning. As a designer, he was also constantly checking the date while naming files at his computer—and preferred not to reach for his phone while working.
What if a perpetual calendar could also be the puzzle?
365 DAYS. 54 SQUARES.
Making the idea work was a puzzle in itself.
A standard 3×3×3 puzzle cube has 54 visible squares: six centers, 24 corner faces and 24 edge faces. Sean began by breaking the calendar down using those same constraints.
The abbreviated months provided the first breakthrough. Looking at JAN, FEB, MAR and the remaining months, Sean discovered there were exactly six unique middle letters.
Six letters. Six centers.
“I remember realizing that and thinking, okay, I might actually be onto something.”
From there, Sean worked through the characters needed to create every day, month and date. Some fit neatly within the available positions; others required more creative solutions. By mixing upper- and lowercase typography and considering how characters appeared when the cube was rotated, individual characters could perform double duty—a capital J could become a lowercase r when inverted, for example.
Eventually, every letter and number found its place.
All 365 dates fit.
DESIGN PROCESS
On paper, the system worked. Now Sean needed to prove it physically.
Using masking tape and a Sharpie, he labelled an old puzzle cube and began testing dates.
“I remember the moment vividly. It was July 2023. Once I could see that it actually worked, it was a real eureka moment.”
As a member of the Design Fabrication Zone at Toronto Metropolitan University, Sean had access to fabrication equipment including a large-format UV printer. Working with the fabrication team, he created a custom jig that allowed an all-white puzzle cube to be printed one face at a time.
The result was dramatically different from the masking-tape prototype: crisp black typography printed directly onto a clean white cube. What had begun as a mathematical puzzle was starting to look like a product.
FROM PUZZLE TO DESIGN OBJECT
With the cube resolved, Sean turned his attention to how it would live in the home.
An early 3D-printed case proved the interaction, but moving to wood transformed the character of the product.
“The plastic case made it feel like a product. The wooden case made it feel like a design object.”
Its seemingly simple form hides a series of deliberate details. The 6 mm thick wooden case frames the cube while allowing it to project 4 mm from the front—just enough to communicate that it’s a three-dimensional object meant to be removed and played with.
The case sits at a 15-degree viewing angle and tips forward with the touch of a finger, allowing the cube to be removed with one hand. Tight tolerances create a cushion of air behind the cube, gently slowing it as it settles back into place.
Working together, Sean and the Umbra Design Studio refined the prototype for production while preserving these interactions and elevating the construction and finish of the final design.
“I want things to feel simple, but I want that simplicity to come from deliberate choices. The details may not jump out at you, but you feel them when you interact with the product.”
A DAILY RITUAL
Play Date was designed to capture the satisfaction of solving a puzzle cube without the intimidating learning curve of solving all six sides.
Unlike a traditional 3x3 cube, there are no algorithms to memorize. Because only one face needs to be completed, each date can be assembled through a handful of twists. The goal isn’t speed or mastery, but a small daily challenge—an analog counterpart to the digital puzzles that inspired it.
“I wanted something that would engage your brain, your fine motor skills and that hand-eye coordination. Just a little ritual to get your mind and body going in the morning.”
That combination of playfulness and considered problem-solving reflects something Sean strives for throughout his work.
“Clever design has a bit of a wink to it. Something a little magical, a little tricky—something that makes you stop and think, ‘Oh, that’s really cool.’ But underneath that, it has to be deliberate, smart and thought through.”
When Sean first showed the concept to longtime toy inventor and mentor Paul Reynolds, his reaction captured it succinctly:
“This calendar is deviously clever.”
But the ultimate measure of Play Date’s success isn’t simply whether people appreciate its cleverness. It’s whether they make it part of their day.
At Umbra’s 40th anniversary celebration, Sean ran into VP of Design Matt Carr. When Sean started to reintroduce himself as the designer of the Calendar Cube, Matt stopped him. Of course he remembered—he solved the cube every morning.
“To create something that someone actually puts their hands on and gets a little bit of joy from every single day—that’s about as good as it gets for an industrial designer.”
Once solved, Play Date returns to its wooden case and becomes a functional perpetual calendar until it’s time to solve it again tomorrow.
A calendar you don’t just look at.
You play with it.
