Not every solid has to be extruded from a 2D shape. AutoCAD has seven commands for basic solids: box, cylinder, cone, sphere, wedge, torus and pyramid. For round piles, pile caps, tanks and pyramid roofs, typing the primitive directly is fastest. This article is a guide to creating 3D solids in AutoCAD with those seven commands, with each volume read back from the program and checked against its formula.
All tests use AutoCAD 2027 and the acadiso.dwt template. Building solids from 2D shapes is covered in the extrude command. For 3D modelling taught properly, the Institute runs an AutoCAD course for construction.
Seven commands
| Command | Alias | Creates |
|---|---|---|
BOX | Rectangular box | |
CYLINDER | CYL | Cylinder |
CONE | Cone or frustum | |
SPHERE | Sphere | |
WEDGE | WE | Wedge (half a box, cut diagonally) |
TORUS | TOR | Torus (a ring) |
PYRAMID | PYR | Pyramid or truncated pyramid |
All seven are on the Modeling toolbar; BOX, CYLINDER and CONE are also under Draw → Modeling. Aliases come from the 2027 acad.pgp file. According to the Autodesk documentation on BOX, a box's length runs along X, its width along Y and its height along Z of the current coordinate system.
The BOX command: three routes to one box
BOX asks Specify first corner or [Center]:, then Specify other corner or [Cube/Length]:, then Specify height or [2Point]:.
| Route | Type | Volume |
|---|---|---|
| Two base corners, then height | 0,0,0, 2000,1000,0, 500 | 1 000 000 000 |
| Cube | First corner, C, 1000 | 1 000 000 000 |
| Length, width, height | First corner, L, 2000, 1000, 500 | 1 000 000 000 |
| Negative height | Two corners, -500 | 1 000 000 000, from −500 to 0 |
The box command with Length asks separately for Specify length, Specify width and Specify height, useful when you have dimensions but no corner points. A negative height pushes the box down, handy for pile caps set from ground level.
The CYLINDER command and cones
The cylinder command asks for the base centre ([3P/2P/Ttr/Elliptical]), the radius ([Diameter]) and the height ([2Point/Axis endpoint]). Radius 500, height 1000 gives 785 398 163, exactly π × 500² × 1000.
CONE asks the same, but its height prompt adds Top radius. Without it you get a pointed cone: radius 500, height 1000, 261 799 388, exactly a third of the cylinder with the same base and height.
A frustum of a cone: the Top radius option
There is no separate command for a frustum; it is CONE with T, in five prompts.
| Step | The prompt | What you do |
|---|---|---|
| 1 | Specify center point of base or [3P/2P/Ttr/Elliptical]: | Pick the base centre |
| 2 | Specify base radius or [Diameter]: | 500 |
| 3 | Specify height or [2Point/Axis endpoint/Top radius]: | T |
| 4 | Specify top radius <0.0000>: | 250 |
| 5 | Specify height or [2Point/Axis endpoint]: | 1000 |
A frustum of a cone with radii 500 and 250 and height 1000 has a volume of 458 148 929, matching π × h / 3 × (R² + R × r + r²). Think belled pile toes, hoppers, tapered round column bases.
Sphere, wedge, torus
| Command | Size | Volume | Formula |
|---|---|---|---|
SPHERE | Radius 500 | 523 598 776 | 4/3 × π × r³ |
WEDGE | 2000 × 1000, height 500 | 500 000 000 | Half the box of the same size |
TORUS | Radius 1000, tube 200 | 789 568 352 | 2 × π² × R × r² |
WEDGE asks exactly like BOX and gives exactly half the volume of the matching box: good for single-pitch roofs, ramps and tapered beams. TORUS asks for the ring radius (Specify radius) and then the tube radius (Specify tube radius); the ring radius runs from the centre of the torus to the centre of the tube.
The PYRAMID command: which radius?
The pyramid command is the easiest of the seven to get wrong. On start, the 2027 release reports its current state:
4 sides CircumscribedIt then asks for the base centre, Specify base radius or [Inscribed]:, and the height. The radius means different things in the two modes. Same radius 500, height 1000:
| Mode | Base | Volume |
|---|---|---|
| Circumscribed (default) | Square around the R500 circle: side 1000 | 333 333 333 |
| Inscribed | Square inside the R500 circle: side 707 | 166 666 667 |
The volumes differ by exactly a factor of two. The reason is geometric. A square drawn around a circle of radius 500 has sides of 1000 and an area of 1 000 000. A square drawn inside the same circle has its corners on the circle, sides of about 707 and an area of 500 000. Everything else about the pyramid stays the same, so the whole difference comes from how the one number you typed is interpreted. The bounding box of the Inscribed pyramid still runs from −500 to 500, because its corners sit on the axes. And the trap: the mode is remembered. After one use of I, the next PYRAMID with no option typed also gives 166 666 667. For a 1000-wide base, read the first line of the command and, if it says Inscribed, type C at the radius prompt. Sides changes the number of base edges; Edge lets you draw the base from the two ends of one edge.
Where the solid sits relative to your pick
The first point means different things in different commands. The bounding box of each solid shows where it lands.
| Command | First point | Solid spans heights |
|---|---|---|
BOX | A base corner, 0,0,0 | 0 to 500, base on the plane |
CYLINDER, CONE | Base centre | 0 to 1000, base on the plane |
SPHERE | Centre, given at height 500 | 0 to 1000 |
TORUS | Centre, height 0 | −200 to 200, half below the plane |
Box, cylinder and cone stand on the working plane; sphere and torus use your point as their centre, so half of them lies below it. To rest a sphere on a floor, give its centre a height equal to its radius, as the example did with 18000,0,500 for radius 500. The torus's bounding box is 2400 wide, exactly 2 × (1000 + 200).
Choosing a solid for the element
| Element | Solid | What to enter |
|---|---|---|
| Pile cap, plinth, beam, square column | BOX | Two base corners and height, or L then length, width, height |
| Round pile, round column, cylindrical tank | CYLINDER | Centre, radius, height |
| Belled pile toe, hopper, tapered round base | CONE with T | Base radius, top radius, height |
| Ramp, single-pitch roof | WEDGE | As for BOX: two base corners and height |
| Pyramid roof, pyramidal column head | PYRAMID | Check the Circumscribed line before the radius |
| Spherical tank, dome | SPHERE | Centre at a height equal to the radius |
Look at the element, pick the nearest solid, then cut or hollow it as needed; that is usually much quicker than drawing a 2D shape and extruding it.
After the solid: cut, hollow, combine
Basic solids rarely stand alone. The usual next steps:
| Job | Command | Article |
|---|---|---|
| Holes and pockets | SUBTRACT, PRESSPULL | Holes in 3D solids |
| Cut along a plane | SLICE | The SLICE command |
| Spin a profile around an axis | REVOLVE | The revolve command |
| Hollow into a thin shell | SHELL | The SHELL command |
For example, a pile cap with a pocket for the column stub: BOX for the cap, CYLINDER for the pocket, then SUBTRACT the cylinder from the box. The remaining volume is exactly the box minus the cylinder, and since both solids match their formulas to the unit, the result can go straight into a concrete estimate.
Three things often repeated that are not true
| Often repeated | What holds on the 2027 release |
|---|---|
| A frustum must be made with REVOLVE | CONE with Top radius makes a frustum of 458 148 929 |
| A pyramid's radius runs from centre to base corner | The default is Circumscribed: radius 500 gives a 1000-wide base |
| PYRAMID resets to its default every time | Inscribed is remembered for the next use |
Frequently asked questions
Which commands create 3D solids in AutoCAD?
Seven built-in ones: BOX, CYLINDER, CONE, SPHERE, WEDGE, TORUS, PYRAMID. For more complex shapes, extrude or revolve.
How do I draw a cube?
BOX, pick the first corner, type C, then the edge length.
How do I draw a frustum?
CONE, enter the base radius, type T at the height prompt, enter the top radius, then the height.
Why is my pyramid smaller than expected?
The command is in Inscribed mode from last time. Type C at the radius prompt to go back to Circumscribed.
Can I trust the volumes?
All seven solids match the hand-calculated volumes to the unit, including the frustum and the torus, whose formulas are easy to get wrong by hand. If a volume looks off, check the input rather than the program: a wrong radius mode on PYRAMID is the usual cause.
How do I put a solid below ground?
Use a negative height: a box of height −500 spans −500 to 0.