LEAP!Tracy Holmes1 Comment

'LEAP' DAY 18 covered the basics of cube construction. In this 'Leap' lesson, learn how to make a Cube that's not only bigger, but with the help of some added magnets in all the right places, especially 'attractive'...



The feature of the BTC system are its 2-sided Colour Cards, one for every colour, with the colour itself filling the Colour Side, and lots of data and 'drill-down' info on the Code Side to tell you more about each colour, what it's made of, and where it fits in with all the others. But there are also DIY Cube Cards, standard-sized playing cards that can be scored, folded, and attached together to make 3-dimensional models that complement the Colour Cards and show all the colours in their places according to an 'XYZ' via 'CMY. You can review the concepts of the Colour Cube in other 'Leaps,' including 'Leap' Day 16: What Is A Cube?.


The 6 Cube Cards included in the Colour Basics connect together to make a stand-alone model of colour in its simplest Corners-plus-Connectors version. 'Leap' Day 18: How to Build a Colour Cube, explains how to turn those 6 basic Cube Cards into a 6-sided Colour Basics Colour Cube.


There's also a collection of 54 BTC Cube Cards that can be used to build cubes in the same way. Six of the cards make a BTC Mini Cube that shows the BTC 6 x 6 x 6 model in a smaller hold-in-one-hand version. Here's the BTC Mini Cube next to the Colour Basics Colour Cube:

Each Cube (and any Colour Cube, BTW) has the same 8 Corner Colours. In both Cubes above, you can see White front and centre, with the 6 Corner Hues encircling it at 6 other corners. The only corner you can't see is Black, which is directly (triagonally) behind White on the back side of each of these Cube. The 6 edges connecting the 6 Corner Hues show the colour flows, with 4 mixed Hues connecting each corner in the BTC Cube (on the left) and only 1 Connector Colour linking the corners in the Colour Basics Cube (on the right). 

The other 48 cards in the BTC Cube Cards deck are actually 8 sets of 6, one set for each of the eight Corner Colours: Cyan, Magenta, Yellow, Red, Green, Blue, White, and Black. These cards are used to make the 8 6-sided Cubes that represent each of the 8 Corner Colours in the bigger BTC deck. And these 8 Corner Colour Cubes stack together to make the bigger BTC Colour Cube.

The 3 x 3 x 3 Corner Colour Cubes are built in exactly the same way as the 3 x 3 x 3 Colour Basics Colour Cube. You can refer to that 'Leap' to review the steps for scoring the fold lines, folding the flaps, and taping all the flaps together to make the 12 edges of each 6-sided cube. 

When all 8 Corner Colour Cubes are all built, they will balance together to make the larger 6 x 6 x 6 model (shown above). If you want to make a model that will hold together on its own, you can integrate small magnets into your build. This 'Leap' lesson focuses on how to do that...


Here's what you'll need to prepare your BTC Colour Cube cards with magnets:

  • double-stick tape (Scotch brand is recommended)
  • regular tape
  • 24 1/4" X 1/10" rare earth circular disc magnets
  • 24 'polar pair' letter-coded BTC Cube Cards

OUT-sides AND IN-sides

Every Colour Cube has 6 sides, and is built with 6 Cube Cards. In a stand-alone Colour Cube (like the Colour Basics Colour Cube and the BTC Mini Cube), all the sides (or faces) are visible 'outside' the Cube. In the larger 8-part BTC Colour Cube, there are 8 6-sided Corner Colour Cubes that fit together. On their own, you can see all the sides, but when the 8-part model is built into a single unit, half of the sides connect to one another on the 'inside' and are no longer visible. In other words, each of the Corner Colour Cubes has 3 'outside' sides and 3 'inside' sides.

There are 24 'outside' cards. When assembled, the outside of the larger BTC Colour Cube shows all the Hues, Tints, and Shades. The 'outside' cards are the odd-numbered cards in each Corner Colour Cube set: 1, 3, and 5.

The other 24 cards in the BTC Colour Cube collection are 'inside' cards. They show the Tones (the colours that mix Hue in the middle with Black and White); the Tones are 'inside' a Colour Cube, and these 24 'inside' cards make the 'inside' faces, 3 for each Corner Colour Cube. The 'inside' cards are the even-numbered cards in each Corner Colour Cube set: 2, 4, and 6.

For this part of the project, adding magnets to your BTC Colour Cube cards, you will only need the even-numbered 'inside' cards. You can set the odd-numbered 'outside' cards aside until you start to build your Cubes.


Every Cube Card is marked near the top and the bottom with fine lines to show where the 2 1/2" x 3 1/2" playing card gets scored and folded to create the 2 1/2" square cube side. This step is explained in detail in 'Leap' Day 18: How to Build a Colour Cube

Score all 24 'inside' cards before you attach the magnets. You can score and fold the outside cards at any time (since they don't get magnets), but it may be easier to score all 48 BTC Cube Cards at once, while you have the tools handy (the scoring tools are listed and shown in the previous 'Leap'). 

Take your time to make sure the scoring is crisp and straight. These folds will be the edges of each of your 8 Corner Colour Cubes and the more precise they are, the easier it will be to build each Cube and also to stack them together into the bigger 8-part model.

2. Find the 12 INSIDE pairs

The most important thing to remember when adding magnets to your BTC Colour Cube is this: opposites attract.

There are 24 'inside' cards and they connect 'face to face' in 12 pairs inside the BTC Colour Cube. To make it easier to find each of the connecting pairs, all the 'inside' cards have been printed on the back with a cross-hair bullseye (to ensure that the magnet is aligned in the exact centre of the card) and a 'polar pair' letter code (using the first 12 letters of the alphabet, A through L) that shows how the cards pair up, to make sure there is a north pole on one of the cards and a south pole on the other. 

When the magnets are in place correctly north to south in their pairs on the backs of all 24 'inside' Cube Cards, they will connect into 12 pairs (A connecting to A, B connecting to B, and so on). If the magnet poles are not opposite, they will repel, and your BTC Colour Cube will not hold together as it should.


Each 'inside' card will need an adhesive to attach the magnet to the card. Starting with one of your letter-coded polar pairs, place a small square of double-stick tape over the cross-hair bullseye on each card.


Place a single magnet on the tape of the first card. Use the cross-hair bullseye as a guide to centre the magnet in the middle. 


The polarity of the first magnet doesn't really matter, as long as you use the opposite polarity on the matching 'polar pair' card. Place a second single magnet on the tape of the second card. Use the cross-hair bullseye as a guide to centre the magnet in the middle, and then hold the cards 'face to face' to see if you have the poles aligned correctly. If the magnet poles are opposite, north will attract south and the cards will attach to one another.

If the cards repel, turn the second magnet over and reposition it on the double-stick tape within the cross-hair bullseye.


Once you're sure the magnets are correctly aligned in the centre of the cross-hair bullseye and the poles are attracting rather than repelling, secure the magnets in place with regular tape.


Repeat Steps 3 through 6 with the other 22 'inside' cards, using the letter codes to match them into the remaining 11 'polar pairs, checking each pair of magnets to make sure the poles have been aligned in the centre and placed with their poles in opposite positions, to attract rather than repel.


Once you have all 24 magnets properly placed and secured to make 12 polar pairs of 'inside' cards, you can construct each of your 8 individual Corner Colour Cubes, as described in 'Leap' Day 18: How to Build a Colour Cube.


Once you have all 8 Corner Colour Cubes built, you can use them as the 8 corners of a bigger 8-part BTC Colour Cube. To figure out the placement of each smaller 3 x 3 x 3 cube within the bigger 6 x 6 x 6 model, remember what you've already learned about the 8 Corner Colours and how they connect to one another in a Colour Cube. You can also use your BTC Mini Cube as a 'key,' or use the Colour Codes in each of the squares to sequence and stack the 8 smaller Cubes together.

the 'inside' of the Magenta Corner (l) and the White Corner (r)

the 'inside' of the Magenta Corner (l) and the White Corner (r)

Magenta connected with White

Magenta connected with White


As you build your BTC Colour Cube, use what you've already learned in previous 'Leap' lessons, like how we make 8 different 'All or Nothing' Corner Colours from just 3 element primaries. Remember that the 8 Corner Colours will end up in the 8 corners of the bigger Cube; Cyan, Magenta, and Yellow connect side by side with White; Red, Green, and Blue connect side by side with Black; and opposite complementary Colours (and their Colour Codes) are triagonal opposites.

Cyan (500) is opposite to Red (055)

Magenta (050) is opposite to Green (505)

Yellow (005) is opposite to Blue (550)

White (000) is opposite to Black (555)

Just as the outside faces show the pure Hues and their Tints and Shades, the inside faces of each Cube show the more muted neutralized Tones (due to there being both Black and White in the mix). These are the faces with the magnets, and they are the only ones that will connect to one another. The closer you get to middle Grey in the middle, the closer you get with the digits of the Colour Codes; instead of the codes that have all (5s) and nothing (0s) like the Corner Colours above, the colours in the middle of the Cube have digits in the middle (222, 333, 322, 233, 232, 323, 223, 332).
4 sets of 2 Cubes each

4 sets of 2 Cubes each

2 sets of 4 Cubes each

2 sets of 4 Cubes each

all 8 Corner Colour Cubes connected and held together with magnets

all 8 Corner Colour Cubes connected and held together with magnets


There are lots of places to buy rare earth magnets, also called Neodymium magnets, and NIB magnets. There are lots of different sizes, shapes, and strengths. The ones used here are a good fit for this project: small enough to easily attach with the width of the tape, strong enough to hold all the individual Corner Colour Cubes together as an 8-part model, but not so strong that it's hard to take the bigger BTC Cube apart. The supplier we use is Lee Valley Tools.

You can use other suppliers, but try and find something comparable in size and shape, and make sure the magnets are axially magnetized, with the north and south poles located on the flat, circular faces (not on the edges). This is the more common magnetization direction, and it's called 'axial' because the 'pull' is along the geometric axis of the magnet.