What does 3/8 and 5/8 mean?
The odd frequency domes are not exactly half of a sphere. They can either be a little more or less than half. 3/8 and 5/8 are not exact numbers, they are mainly for reference.

How do you put these things together? And what is the meaning of that triangle next to the strut lengths?
All of the domes on this site are based on the icosahedron. The 1v dome is actually an icosahedron with the bottom 5 struts removed. The triangles on the Dome Calculator pages represent one icosa face. I created assembly diagrams for all of the domes except the 1v, and the links to them are as follows:
2v dome
3v dome
4v dome
5v dome
6v dome

If you are building your dome from the bottom up, here is some useful information:
You will need to lay out the appropriate number of struts in a circle to get started. The numbers are given below.
1v dome - 5 struts
2v dome - 10 struts
3v 3/8 dome - 15 struts
3v 5/8 dome - 15 struts
4v dome - 20 struts
5v 3/8 dome - 25 struts
5v 5/8 dome - 25 struts
6v dome - 30 struts

Are the lengths given from vertex to vertex?
Yes, the lengths given are from vertex to vertex. If you are building a dome out of metal pipe by flattening the ends and drilling holes, you will need to add about 3/4" to each end for a total of 1.5" for each strut. If you are building a dome using connectors, you will need to subtract twice the length of the connector (one for each end) from each strut.

The dome calculator is great, but I want to build a dome using feet as my unit of measure. How do you go from decimals to feet or inches?
Here's a walkthrough:
If you want to build a dome with a 12 ft. radius, you would put 12 in the calculator. For the 3V dome (just an example), you get:
A = 4.183
B = 4.842
C = 4.945

For the A strut, the 4 just means 4 ft. The .183 is a little harder to figure out. You want to convert the .183 from feet to inches, so multiply .183 by 12 (12 inches in a foot).

.183 X 12 = 2.196 inches

Now you have 4ft and 2.196 inches, almost there. Now you want to convert the 2.196 inches into 8ths of an inch (I don't think you have to go all the way to 16ths of an inch, unless you enjoy being tortured). You can do this by multiplying .196 by 8.

.196 X 8 = 1.568 (round this up to 2)

This gives you 2/8", so the new measurement is 4' 2 2/8" You should be able to do the other ones now.

Decimal Equivalents:
.12500 = 1/8
.25000 = 1/4
.37500 = 3/8
.50000 = 1/2
.62500 = 5/8
.75000 = 3/4
.87500 = 7/8

It would be nice if we could buy pvc in meters because it would be a lot easier to use the decimal measurements.
Example: 12 meter radius dome (3V)

A = 4.183
B = 4.842
C = 4.945

A = 4 meters and 18.3 centimeters (or 183 millimeters)
B = 4 meters and 84.2 centimeters
C = 4 meters and 94.5 centimeters

What are 4, 5, and 6-way connectors? Do I need those?
You don't need connectors if you are building a dome out of metal conduit with the ends flattened and drilled (or something similar). The 4, 5, and 6 way connectors are just the points where that number of struts come together. The 4 way connectors are all on the bottom, and the 5-ways are where the A's come together. the rest of the connections are all 6-way. you don't need to worry about any more connector pieces. There's a really fine example of what connectors are on this page. It takes a little while to load, but worth it. You have to scroll all the way down to see the connectors.

How do you build a dome out of a bunch of flat pieces?
Well, the pieces are not exactly flat. The struts will need to be bent a little on each end to allow the dome shape to form. The bending angles are as follows:
1v dome: bend 32º on each end
2v dome: bend A's 18º, and B's 16º
3v dome: bend A's 10º, B's and C's 12º
4v dome: bend all struts 7º-9º
5v dome: bend all struts 6º-7º
6v dome: bend all struts 5º-6º

I want to build a model first, but I don't know what to use for materials. Can you help?
I recommend using 1/8" wooden dowels and 1/8" (inner diameter) clear vinyl tubing. You should be able to find these at any hardware store. Just make sure to buy the 1/8" inner diameter tubing. You will also need very small nuts and bolts to hold the tubing together. Just ask the salesperson at the hardware store, and they should be able to help you. Cut the tubing into one and a half inch (1.5") pieces, and punch small holes in the center with a leather punch. You will also need some 1" pieces of tubing for the 4 and 5 way connectors, but punch the holes on one end of these pieces instead of in the center. For the 6 way connectors, you will need 3 pieces of tubing with holes punched in the centers. Put the bolt through all three pieces, screw the nut on, and tighten it. It should look the picture in the diagram I sent. For the 4 way connectors, you will need one 1.5" piece, and two 1" pieces (remember, punch the holes on one end for these, and not in the center). Put the bolt and nut in, and tighten. For the 5 way connectors, use five 1" pieces and bolt them together. This is an example of the 6-way connector for this model.

I'm going to Burning Man this year, and I was wondering what kind of dome you recommend.
I know I used to say that PVC was the way to go, but now the answer is definitely metal conduit. Got to the new Conduit Dome Tips page for more info! PVC is light and a little cheaper, but it doesn't hold up as well. If you paint the ends of the struts on your conduit dome so they don't rust, the dome could last forever. (well, not really but you see what I'm getting at) For smaller domes 1/2" conduit is OK, but don't make the struts any longer than 4'. For larger domes, don't show up at Burning Man with anything less that 3/4" conduit. You don't want to be that camp with the once beautiful dome that just got pulverized by the high desert winds. I know, it happened to me before (long story). Spend the extra money, you won't regret it when the dust storm comes and your structure is the only one left standing. Always bring extra pieces pre-cut and drilled just in case... There always seems to be one pole short, bent, or just plain messed up.

But I really really want to build a PVC dome, how do I do it?
If you have your heart set on PVC, here's a short explanation of the connectors. They are just short (4-5") pieces of conduit slipped into each end of the pvc. Make sure it's a tight fit, you can try them out at the hardware store before you buy them. A couple of sheet rock screws secures the pieces in the PVC. The ends of the conduit are flattened and bent slightly, then a hole is drilled in each one. Don't forget the sheet rock screws to hold the conduit inside the PVC. They are very important, and speaking from experience, don't leave ANY out (long story, same one from above). Two screws in each end. Yes, longer bolts will be necessary for the 5 and 6 way connections. I think I bought 2" long bolts, and they were almost long enough. I think 3" would be plenty long enough.

How do you secure your dome to the desert floor?
For tie downs, we used rebar (at least 2 ft.) bent into a U shape at the end. Every other point on the bottom of the dome got a stake over the conduit that lays on the ground. Pound them all the way in, you don't want any of your fellow playa people getting hurt.