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Models shared by the SO3D.xyz community. Open any of them in the generator to see exactly how it was built, remix it, or print it as-is. Browse the model library by category

Preview of Raindrop-size flour tray
By Krypto
Complexity
Multi-part assembly
MAIN PURPOSE: Measure the size of raindrops by catching them in flour
In 1898, the snowflake photographer Wilson Bentley measured raindrops by catching them in flour: each drop rolls itself into a little dough pellet the same size as the drop. Take the lid off in the rain for a few seconds, cover it again, and let the pellets dry for an hour. Sift them out and drop each through the gauge holes beside the tray, from 2 to 7 mm. Drizzle makes tiny pellets, a summer storm makes big ones, and you can compare showers through the year.
AR view Open in app
Preview of Junior forensic lab
By Krypto
Complexity
Advanced
MAIN PURPOSE: Dust and match fingerprints and unmask a pen with ink chromatography
Two classic detective techniques in one tray. Dust a glass with cocoa, lift the print with clear tape, stick it on a card and compare it with the ARCH, LOOP and WHORL patterns engraved in the bays. Then solve the mystery note: dot ink from each suspect's black pen near the bottom of coffee-filter strips, hang them from a skewer across the INK trough with their tips in water, and watch each ink split into its own bands of colour. The pen whose colours match the note is the culprit.
AR view Open in app
Preview of Micrometeorite hunting kit
By Krypto
Complexity
Advanced
MAIN PURPOSE: Find real space dust in your roof gutter with a wash tray, a magnet sleeve and a loupe
Tonnes of space dust land on Earth every day, and in 2017 the amateur scientist Jon Larsen proved you can find it on city rooftops. Scoop sludge from a gutter, WASH it in water and pour off the mud, DRY it, then pass the MAGNET sleeve through it: most micrometeorites contain iron, so they cling to it. Pull the magnet out over the FIND bay and the grains drop free. Under a 60x loupe, look for tiny shiny spheres with a pattern of crystal stripes, 4.6-billion-year-old visitors from space.
AR view Open in app
Preview of Strawberry DNA extraction lab
By Krypto
Complexity
Advanced
MAIN PURPOSE: Pull visible strands of DNA out of a strawberry with soap, salt and cold alcohol
You can see DNA with your own eyes. MASH a strawberry in a bag with a spoon of washing-up liquid and a pinch of salt (the soap breaks open the cells, the salt clumps the DNA), pour it through a coffee filter in the FILTER cup, then pour the juice into a test tube in the rack. Trickle ice-cold rubbing alcohol down the side of the tube: a white, cloudy, stringy layer rises up through it, the strawberry's DNA, which you can spool out on a stick in the STIR bay.
AR view Open in app
Preview of Buffon's-needle pi tray
By Krypto
Complexity
Medium
MAIN PURPOSE: Estimate pi by dropping matchsticks on a tray of parallel lines
In 1777 the Comte de Buffon found a way to work out pi with nothing but sticks: drop sticks as long as the gap between parallel lines, and the chance that one lands across a line is exactly 2 divided by pi. Drop 40 mm sticks onto this tray, which has raised lines exactly 40 mm apart, count how many you dropped (N) and how many cross or touch a line (C), and pi is about 2N divided by C. A hundred drops gets close to 3.1; a whole class pooling results gets closer still.
AR view Open in app
Preview of Zhang Heng earthquake ball
By Krypto
Complexity
Medium
MAIN PURPOSE: Detect a tremor when a marble balanced on a slender column falls into the dish
In 132 AD the Chinese astronomer Zhang Heng built the first seismoscope: eight bronze dragons each held a ball, and a tremor made one drop its ball into the mouth of a bronze toad, clanging the alarm and showing the direction of the quake. This is the one-dragon version. A marble sits in a shallow cup on top of a tall, slim screw-in column; a door slam, heavy footsteps or a real tremor tips it off and it lands in the dish with a clatter. Place it on different floors and see which part of the house shakes most.
AR view Open in app
Preview of Woodlouse choice chamber
By Krypto
Complexity
Medium
MAIN PURPOSE: Let woodlice choose between damp, dry, light and dark, and count where they go
A classic biology experiment. The four bays meet at an open centre: DAMP and DARK, DAMP and LIGHT, DRY and DARK, DRY and LIGHT. Release ten woodlice in the middle, cover the top with cling film, shade the DARK half with card and wait ten minutes. Almost all of them end up in the damp, dark bay, because woodlice are crustaceans that dry out quickly and hide from the light that would show them to birds. Count them, swap the conditions round and try again, then return them to where you found them.
AR view Open in app
Preview of Ames-room illusion box
By Krypto
Complexity
Simple
MAIN PURPOSE: Make two identical toys look like a giant and a dwarf through a peephole
Look through the peephole and the room looks like an ordinary box, but it is not: the back wall runs at a slant, so the left corner is twice as far away as the right. Put two identical figures in the back corners and one looks like a giant and the other like a dwarf. Move a figure along the back wall and it grows or shrinks before your eyes. It is the Ames room, invented in 1946 and used in films to make actors look tiny next to wizards.
AR view Open in app
Preview of Cloud-chamber cosmic-ray base
By Krypto
Complexity
Simple
MAIN PURPOSE: See the trails of cosmic-ray particles in a home-made cloud chamber
Invisible particles from space pass through you every second, and this lets you see them. Put a slab of dry ice in the base, lay a 3 mm aluminium plate painted matt black on the ledge, and turn a clear plastic tub upside down on the plate with a strip of felt soaked in 99% isopropyl alcohol stuck inside its top. After ten minutes, turn off the lights and shine a torch in from the side: thin white trails appear and vanish as muons, alpha and beta particles streak through the alcohol mist, just as in the chambers that won Nobel prizes.
AR view Open in app
Preview of Phone-screen photoelastic viewer
By Krypto
Complexity
Simple
MAIN PURPOSE: See the hidden stress in clear plastic as rainbows using a phone screen
Your phone screen gives out polarised light, which is half of a stress lab. Lay the phone in the bottom showing a white page, slide a piece of clear plastic in through the slot (a protractor, a CD case, a plastic fork) and put polariser film on the ledge above. Look down and the plastic lights up in rainbow bands wherever it is strained. Squeeze the fork and watch the colours race. Engineers use exactly this, called photoelasticity, to find weak spots in parts.
AR view Open in app

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