Parabolic mirrors are used to concentrate and redirect sunlight. It would be a kind of solar thermal energy center. All with a main material as simple as the thermal blanket, which can be obtained at low prices in specialized stores.
The entire manufacturing process involves the use of compressed air to form a polyethylene terephthalate sheet (or isothermal blanket) on the parabola. This is accomplished by securing that material to a flat surface that will be pressed from below like a giant cell of bubble wrap.
The first part of this project will be the surface to inflate the isothermal blanket. It begins by using a PVC sheet as a material, because the air does not pass through it and it is perfectly flat. Air injection will be needed from the center of the square plate you need to form.
The first step to achieving this is to mount a bicycle tire inflation valve on a small piece of trim. Then a hole is drilled in the middle of the base and with some PVC cement, that cut piece that carries the valve will be glued to the stem and facing outwards.
On top of the PVC, make a silhouette the size of the mirror you want to create by tracing with a marker, then sandpaper just outside the line so the glue adheres well.
Now you take the isothermal blanket sheets and stretch them over the entire base, but keep in mind that they usually come folded in small wrappers, so you have to stretch them and remove all those marked folds.
Apply epoxy around the circle you sanded earlier and place the stretched isothermal blanket on top. When it is well glued, you will turn on the tire valve and begin to inflate the mirror. You will see how the parabola is formed and to keep it solid, you must apply fiberglass on top and wait for it to dry. Once you have done it well, apply two more coats and if you want, speed up the process using a hair dryer.
When everything is completely dry, use an angle grinder to cut the dish. Clean the result and you will see that the reflection in the isothermal blanket is very good. To keep the round shape, use some kind of tape or material that you have at home completely solid that surrounds the parabola creating the same shape. Put a weight on it and glue it with putty.
Once it is dry, you would have ready the last step to obtain the parabolic mirror.
If you want to see all the ingenuity applied by Ben, from the creators known as NightHawkInLight, you will see that before concluding that the parabolic shape can be achieved with layers of fiberglass, he tried to apply spray foam, but failed in the tried: