Five dome shapes
- Round is half a sphere, the classic dome for towers, halls and biodomes. It gives exactly the same blocks as Dome mode in our sphere generator: a hollow 21-wide dome is 11 layers and 569 blocks.
- Elliptical sets width, depth and height separately. Make it lower than half the width for a flat roof, taller for an egg-shaped tower top, or give it different width and depth to cover a long hall.
- Onion swells out wider than the tower it sits on, then pulls in to a spire, like the domes of Russian churches. You set the bulb width, the base (neck) width and the height.
- Pointed is made of two arcs that meet at a point, like a gothic arch spun round. The default height is the equilateral arch, about 0.87 times the width.
- Saucer is a shallow slice of a much larger sphere. Unlike a squashed elliptical dome, it meets the walls at an angle, the way many large stone domes do. The Big hall 41 shallow preset is 11 layers high and takes 1,337 blocks.
Match the dome to its base
A dome only looks right when its bottom layer lands exactly on the wall below it. Every dome on this page starts with its base layer, and that layer has the same outline as a circle of the same diameter. So if your tower is a 21-block circle, make a 21-block dome; build the walls with the circle generator at the diameter shown under the stats, stack them as high as you like, and start layer 1 of the dome on top.
For an onion dome, the number that has to match the tower is the base width, not the bulb. The bulb hangs out past the tower on every side, which is what gives the onion its shape. Keep the base 2 to 4 blocks narrower than the bulb for small domes and a little more for big ones.
The base ring option adds one extra layer under the dome. Ring under the dome has the same outline as the dome's base, handy as a first course in a different block. Cornice is one block wider on every side, so it sticks out like a ledge where the wall ends and the dome begins. Pick a separate ring block under the export settings to make it stand out.
Plan the size before you choose a spot. A round dome is half as tall as it is wide, but pointed and onion domes can be taller than their width: a 21-wide onion at the default height is 32 layers. The stats show the full size as width × height × depth.
How to build a dome layer by layer
- Mark the center. Put a marker block where the middle of the dome goes. The yellow lines in the chart cross at the center, and the faint lines count every 5 blocks out from it.
- Build the bottom layer. Count out from the center to the edge in all four directions, then fill in the ring. It is worth doing this first layer in a cheap block such as dirt to check the outline.
- Step up. Press ▶ (or the right arrow key), go up one block and place the next layer. The faded blocks show the layer below, and the text above the chart says how many blocks the new layer has compared with it.
- Watch the steps. Near the bottom, each layer is almost the same as the last. Near the top, layers shrink quickly; the side profile shows where the wall steps in, so you can see what is coming.
- Close the top. Finish with the cap, the skylight ring or the spire.
The layer list under the 3D view gives the block count of every layer and a running total, so you can bring the right amount of material for each session. Print all layers makes a sheet with every layer as a small numbered grid; choose Save as PDF in the print dialog to keep it on your phone. Our step-by-step dome building guide covers marking the base and common mistakes in more detail.
Scaffolding tips for survival
Scaffolding, crafted from bamboo and string, is the easiest way to reach the upper layers. You climb up by jumping inside it and go down by sneaking. In Java Edition it can reach up to 6 blocks sideways from a supported block before new pieces fall, so a central tower with short arms covers a small dome. For a large dome, put up a few towers inside the shell rather than one long reach.
Clearing up is quick: breaking the bottom block of a column breaks all the scaffolding above it. Build the shell from the inside where you can, since you can then stand on the layer below and place each new block on its inner edge.
Onion and pointed dome tips
- The underside of an onion bulb overhangs the tower. Build the first few widening layers from scaffolding on the outside, or from the inside before the bulb closes in.
- The top of both shapes ends in a column of single blocks. Finish it with a lightning rod, an end rod, a fence post or a block of gold for a finial.
- Bright colors work: onion domes are traditionally gold, green or patterned. Try gold blocks, waxed copper or a stripe pattern of two concretes.
- A pointed dome with a 2- or 3-block wall reads better from far away, because the thicker wall keeps the steps near the tip filled in.
Glass domes
Use full glass blocks, not panes. Panes connect to their neighbors and look ragged on a curve, while blocks keep the outline clean. Glass only drops if you break it with a Silk Touch tool, so a misplaced block is lost without one; build the outline in a cheap block first if you are unsure. Glass is made by smelting sand or red sand.
Tinted glass, crafted from glass and amethyst shards, is see-through but blocks light, which is useful for a dark observatory. It also drops itself when broken, without Silk Touch. A glass dome with a stone or copper base ring, or with a few solid ribs running from the base to the top, looks far more finished than plain glass.