Magnet Cairn: Impossible Cantilever Stacking Sculpture

Five coloured geometric pieces stack with hidden magnets so a long slab appears to float far past its support, and you can restack it into a new composition.

Date: 2026-11-13 Category: Art and Decor Modeling difficulty: Beginner Estimated print: ~9.1 h total · ~135 g PLA (estimate) Suggested price: $40–$65 printed · $5 digital file (estimate) Status: Concept

Description

Magnet Cairn is a stone-balancing sculpture made of printed shapes. A low foot carries a drum, a long slab, a cube and a half-dome. In the default pose the slab hangs 43 mm past the edge of the drum and the cube and cap sit on the far end. Without magnets that stack would fall over.

Each flat face has three small magnet pockets in a row. Slide a piece along the row and it clicks into a new offset, so the sculpture can lean, cantilever or sit square. All pockets are filled the same way, so any piece attracts any other.

The pieces are smooth, rounded solids in teal, terracotta and cream. The seams between them are the only visible lines.

Why it sells

Art idea: the evidence is inspiration. Stone stacking is a recognised art practice (Wikipedia), and Michael Grab is known for balances that look impossible (Wikipedia). Rocks are outdoors and fragile. A printed, magnet-held version can live on a cabinet and survive a knock. I did not collect sales numbers. The gap: balance sculptures are either real stones or toy stacking blocks, not coloured modern pieces that are meant to be re-posed.

Who buys it

People who like the stone-balance look but want it indoors: design-minded home owners, office desks, gift buyers. It also suits anyone who fidgets and likes to rearrange things. Sold through Etsy, craft fairs and design shops.

Design overview

• Five solids: stadium foot, drum, long slab, cube and half-dome.
• 24 magnets in three-pocket rows on every contact face.
• Default pose has a 43 mm overhang of the slab past the drum.
• Rounded edges (2 to 4 mm) on every piece.
• No supports: every part prints flat.
• What sets it apart: the magnets let a 104 mm slab and its load hang past the drum, a pose real stone cannot hold, and the pose can be changed.

Dimensions

Parts list

Hardware and non-printed parts

• 24 × 8 mm × 3 mm N52 neodymium disc magnet (foot 3, drum 6, slab 6, cube 6, cap 3)
• Cyanoacrylate glue
• Pull force for 8 x 3 mm is not published by the supplier I checked; the nearest size, 9 x 3 mm N52, is listed at about 2 kg (supermagnete). Test one pair before printing the set.

Fits and tolerances

• Magnet in pocket: press and glue, 0.1 mm per side (8.2 pocket for an 8.0 magnet).
• Piece on piece: flat contact held by magnets, no clearance.
• Pocket depth 3.2 for a 3 mm magnet leaves it 0.2 mm below the surface so the faces still meet.
• Remaining wall in the 14 mm pieces between top and bottom pockets is 7.6 mm.

Modeling guide

Origin: centre of the part's bottom face, +Z up, +X along the long side.

1. Foot. Sketch a 110 × 62 stadium on XY, extrude 14, fillet the top edge 3 and bottom edge 1, cut three 8.2 mm pockets 3.2 deep at X = -20, 0, +20 in the top face.
2. Drum. Circle d58, extrude 36, fillet both edges 2, cut three pockets at X = -20, 0, +20 in both end faces.
3. Slab. Rectangle 104 × 46, corners 7, extrude 14, fillet edges 2, pockets at X = -20, 0, +20 in both faces.
4. Cube. Square 40, extrude 40, fillet all edges 4, pockets at X = -12, 0, +12 in both faces.
5. Cap. Revolve a quarter circle radius 22 about Z, cut three pockets at X = -12, 0, +12 in the flat face.

Print settings

Assembly

1. Use one marked magnet to check polarity of every other magnet before gluing.
2. Glue magnets into top-face pockets with N facing out and bottom-face pockets with S facing out.
3. Let the glue cure for 30 min, then stack in this order: foot, drum, slab offset +20 mm, cube at the slab's +20 mm pocket, cap centred.
4. Re-pose by sliding pieces to a different pocket row.

Variants and upsells

• Pastel and primary colour sets.
• A bigger set with 10 × 3 mm magnets and 140% scale.
• Add-on pieces: arch, wedge, ring, each with the same three-pocket rows so they join the set.
• A series: one new shape each month.

Selling and distribution

Sell printed sets on Etsy and at markets; sell the file on Printables or Cults3D with a commercial licence. Price from 135 g of PLA, 24 magnets and 9 hours of machine time plus margin. Keywords: balancing sculpture, magnetic stacking art, cairn sculpture, modern shelf decor, geometric desk toy, cantilever sculpture, stone balance decor, colourful 3D printed decor, rearrangeable sculpture, magnetic desk sculpture.

Risks and IP notes

• Magnet safety: small neodymium magnets are a swallowing hazard. Mitigation: glue them in, add "not for children under 14" to the listing, never describe it as a toy.
• Strength: the pose depends on the pull of 8 mm magnets. Mitigation: test one pair; use 10 × 3 mm if the pull is weak.
• Polarity errors: reversed magnets repel. Mitigation: mark the first magnet and check each one.
• Saturation: balancing stacks are common. Mitigation: the re-posable magnets and the colour palette.
• IP: stone-balance art is a style, not protected; do not use any artist's name in listings.

Resource links

• Rock balancing — stone stacking as art
• Michael Grab — impossible-looking balances
• 9 x 3 mm N52 disc magnet — nearest published magnet size and pull force
• Josef Hartwig — plain geometric solids as a design reference