DO NOT attempt this build. It is actually pretty dangerous, with large (sixty-pound), near-frictionless, three-pointed weights suspended above your head, aiming for your feet. They can crush you or spear you or cleave you. Once fully completed it is safe, but only temporarily. Do not attempt this on any property where you cannot 100% control access. Do not attempt this if there is any possibility of unauthorized access. The dome will eventually melt, and will collapse, and you cannot predict when. It weighs enough to be potentially fatal. It is advisable to intentionally destroy the dome once above-freezing weather is expected to stay.

If you disregard this warning, then plan ahead. The preparation will take some time but is necessary to deploy as fast as possible once an expected run of below-freezing weather starts.

Calculate the size and shape of the triangular panels. The dimensions will depend on the size of the dome and the geodesic basis shape. The dome here was based on a second order tessellation of the rhombic triacontahedron. (Many geodesic domes are based on the icosahedron, but I think that the triacontahedron gives you the best bang for the buck on low number of unique triangular shapes and high spherical approximation.)

Obtain wooden planks (they don’t have to be wood but it is inexpensive and easy to cut). Make edge cross lap joints so that they form the triangles calculated in the previous step. Note that you can angle the joints as I did so that the edges of the resulting panels bevel according to the spherical radial direction, but it is not critical to do so. The approximated sphere is determined by the edge lengths, not the bevel angle.

Cut plastic sheeting into shapes larger than the triangles, at least a foot larger in radius from the centroid of each triangle. It is good to make them a good bit larger so that the same shape can be used with any of the unique triangular shapes. They get mixed up when it’s windy out. Excess sheeting will also aid in ice panel removal.

Plan out construction site. It helps to have snow on the ground, but is not mandatory. I used a 9.5 foot rope staked to the center of a circle to trace out the extents of my hemispherical dome. Note that my build was not on level ground, so I had to adjust my model to choose a good alignment of triangles with respect to plumb.

Once the dome periphery is marked out, level some patches outside of the dome (again, helps if you can use snow for this purpose). These level patches will be your triangle farm. I had four distinct shapes (really three because one was a mirror of the other), so I made 36 triangles, or 9 sets of each shape. I needed a total of 120 triangles to form a complete hemisphere. The actual final number used was less, since I needed a doorway. The actual final number of panels made was much more, due to casualties of panels for various reasons. But this means at minimum, each mold needed to be used 4 times to freeze enough panels to complete the dome. In practice it was more like six times. The trick here is to have enough time of sustained cold weather to do this. With this method, the panels take the better part of a 24 hour day to freeze, with temperatures not so far below freezing. The larger your site, the more panels you can do at once, the better chance you have to complete this project while the weather holds.

Inside the dome, create areas to store the final panels. Classify them by shape. They will all look pretty similar and it will get confusing. Paying attention here will save a lot of time later. As the dome is raised, the panels inside will be protected, especially if there is a temperature excursion or direct sunlight.

Place triangular wooden forms on top of leveled snow regions. Place plastic sheeting inside forms such that they for a waterproof “cup”. This is the triangular panel mold. At the corners there will be some folds. Make sure they fold flat against the side such that any trapped water will break and flake off when removed. Fill form with water. The colder the water starts, the better it is for a lot of reasons.

Wait until frozen.

Release panels from molds. The ice is heavy, but will pop out of the plastic sheeting. Do not tear the sheeting, or puncture it on any sharp features the ice may form. Put panels in appropriate locations inside dome periphery. Replace sheeting and refill with water.

While new batch is freezing, start to lay the triangles down according to the plan. A small model can help with visualizing the placement. If you used ¼ inch wood as I did, you will see that the weight of the water pushed out the sides slightly, so that the triangle edges are not quite straight. This is OK. The shapes will not be perfect, and there will be an inch or two variation in panel dimensions. This can be adjusted for with a little mortar made of snow and water. It is also why the slight bevel angle does not make a difference. The other dimensional variations result in the actual bevel angle of each panel being negligible. Set each panel with the snow mortar, and place them as precisely as possible according to their edge lengths.

Be careful. Take breaks. Drink water. Warm up periodically.