The shape of the pyramid, of course, offers many possibilities in the design of colored glass. A pyramid consists of four flat sides. So you do not need a mold on which to build the lamp. You first finish soldering the four flat sides individually and then put them together to form the pyramid.
Pay attention to dimensional accuracy! Of course, it is especially important that the transitions to the next side fit. I always say " Who can work imprecisely, can also work precisely " and that is easier than you think.T