How to Build a Small Half Dome?
cchatterj1234@gmail.com, October 1, 2025.
Introduction
For small decorations and art projects, it is easy to build rectangular structures by joining wood. But it is a challenge to build a small dome like the one below:
I wanted to build this dome that is 22” wide and 15” high. The method described here is for a half dome but it can be easily extended to a full dome. Also the method can be extended to a dome of any other size within reasonable limits.
Length of the Arch
Note that the dome is an inverted parabola like the picture below.
Let us assume that we want a dome of height H and width 2W. Then the equation of the parabola is:
y = -(H/W²)x² with x between -W and W.
What is the length L of this parabola for x between -W and W?
Given a parabola y=cx² the length of the parabola for x between -W and W is:
Given H=15, W=11, c=H/W²=0.124. So we have L = 38.93 ≈ 39.
Steps to Build a Half Dome
Now that we know the length of the parabola how do we implement the half dome that is shaped like this parabola?
Note that I am building a half dome — you can extend the method for a dome.
My half dome is 11” radius and 15” high, arc length 39”.
Here are the steps.
Build the Base
Take a 5 mm plywood that is slightly bigger than the dome diameter i.e. > 22”. I took a 24” wide by 15” long 5 mm thick plywood.
Draw a semicircle that is 11” in radius with center in the middle of the back edge.
Install a 2” PVC pipe with L brackets.
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See picture below.
Layer the Base
Next place a layer of wood below the base so that the wire frame does not stick out of the plywood base.
Layer the 2” Pipe
Insert a 1” PVC pipe through the center of the 2” PVC pipe and secure the 1” pipe with a screw through the 2” pipe. The 1” pipe will prevent the wire mesh from going too far into the 2” pipe.
Buy Rods
Buy rods that are half the length of the arch which in our case is half of 39”, i.e. 19.5”. I bought 20” long rods. The tensile strength of the rods is very important so that there is a good medium of bend strength and flexibility. For me the 2.5 mm thick stainless steel wires worked great. I bought 10 wires because if they are too crowded at the top of the pvc pipe the pipe can shred.
Insert the Wires
Make 2.5 mm holes evenly along the radius of the 11” circle on the plywood and at 15” height on the 2” pvc pipe. Make sure the holes do not go through the plywood layering and the 1” PVC pipe which is the pipe layering.
Now insert the wires between the 2” PVC pipe and the plywood base.
Cover With Tape
Next I covered the wires with white tape to make one continuous surface between the wires.
Plaster the Tape
I now put a layer of plaster on the taped surface. Once dried lightly sand the surface.
Tape the Plaster
In order to smooth the hardened plaster surface I used another layer of matte off-white painter’s tape.
Paint the Half Dome
Next I painted the half dome with the color of my choice.
Final product
After some embellishments.
Hope this helps and you can build it too.
