Creating shell mobiles with natural materials

Gathering with care

Half the pleasure of a shell mobile begins on the beach, not at the workbench. A good piece is never bought in a bag; it is collected slowly over a winter or two, one pocketful at a time. The best material is already worn by the sea — cockles and mussels with their hinges gone, limpet hats, slipper shells, the occasional fragile razor clam, and the smooth frosted shards of sea glass that turn up wherever there has been a bit of old industry along the coast.

Take only what is loose and empty. Never prise a shell off a rock or lift one that still has an occupant, and leave anything attached to a living creature well alone — a limpet on its scar, a whelk with its egg cases, a crab in a whelk shell. Check local byelaws before you pocket anything, particularly on nature reserves and Sites of Special Scientific Interest, where collecting is often restricted. A handful from a public beach is plenty. If a shell still smells of the sea after a week in your pocket, it was not empty.

Rinse your finds in fresh water and leave them to dry on a tray for a few days. Fresh water dulls some shells slightly, but it removes the salt that would otherwise crystallise and flake the surface indoors. Sea glass needs nothing more than a wipe.

What you will need

• A hand drill or a rotary tool with a fine bit, 1.2 to 1.5 mm
• A small dish of water and an old towel
• Low-tack masking tape
• Waxed linen thread, fine nylon cord, or 8 lb fishing line
• Clear-drying craft glue and a darning needle
• A piece of driftwood, a bamboo hoop, or a wire ring for the frame
• Eye protection and a dust mask

Do not skip the last item. Shell dust is fine calcium carbonate and it is unpleasant in the lungs. Work outdoors or beside an open window.

Drilling shells without cracking them

This is the step that decides whether you have a mobile or a pile of fragments. The principle is simple: go slowly, keep the bit cool, and let the drill do the work rather than your hand.

Lay the shell on a folded towel so it is supported along its curve, never balanced on a single point. Place a strip of masking tape over the spot where you intend the hole; it stops the bit skating across the surface and reduces chipping at the edges. Mark your point with a pencil.

Use the lowest speed your tool offers and press very lightly. Lift the bit every second or two to clear the dust — a pecking motion. Dip the bit in water regularly, or dribble a little from a teat pipette, to stop it overheating. A hot bit will scorch and crack thin shell in an instant.

For flat shells such as oyster or scallop halves, drill from the outside in. For curved shells, drill toward the thickest part of the shell — usually the hinge area on a cockle or the crown of a limpet. On sea glass, work even more gently: it is brittle and will chip if you rush. A diamond-coated bit lasts far longer than a masonry one on glass.

If a shell cracks, keep the pieces. Broken shell threaded on a string makes excellent spacer beads and looks deliberate rather than damaged.

Choosing the thread and tying secure knots

Cotton rots. Wool stretches. Ordinary sewing thread snaps in a breeze. Use waxed linen, bonded nylon, or fishing line — something that will hold a knot and shrug off damp air near a window.

Thread each shell with a darning needle, then secure it with a small overhand knot above and below so it cannot slide. Finish every knot with a pinhead of clear craft glue and leave it to cure for an hour. This single habit will save you from a slow-motion collapse six months from now.

Leave a long tail at the top of each string while you work. You will trim it at the end, once everything is balanced.

Balance is everything

A mobile is a set of levers, and it only looks effortless when the weights are right. Pair shells of similar mass at each level, and hang the heavier pairs on the lower tiers where they will not overpower the whole piece.

The simplest sturdy design is a driftwood cross or a bamboo hoop with four to six strings dropping from it at even intervals. Bring the strings together above into a single loop for the ceiling hook — the point where they meet should sit directly above the centre of the frame, or the whole thing will hang at a slant.

Test the balance before you finalise anything. Hold the mobile up and let it settle, then adjust by sliding knots rather than cutting. If one string sits heavy, add a small piece of sea glass as a counterweight. Hang it outdoors on a still day first to check that the tiers do not tangle; nothing ruins a mobile faster than strings that twist into each other.

Hanging in the window, and looking after it

The best spot is a window that catches morning or late afternoon sun, where frosted glass and pale shell will glow from behind. Fix a small brass cup hook into the ceiling joist or window reveal, not into plasterboard alone, and hang the mobile with enough clearance that it turns freely.

Expect to dust it twice a year with a soft dry brush — never a damp cloth, which will leave streaks on both shell and glass. Check the knots each spring, particularly if the mobile hangs near a frequently opened window. Sea glass fades nothing and shells only mellow, so with a little care this is an ornament that will outlast the beachcombing coat you wore to find it.