The preparation starts with the creation of a model of the object / sculpture as a 3D volume, most often using sculpting clay (though polystyrene or other materials are equally possible). Then, the model is surrounded with a special mixture with a plaster base, producing the mould with a negative relief inside, into which the melted glass is later poured. Often, the mould is divided into sections for better ease in handling because of the mass; for larger pieces, the glass can be reinforced by inserting iron rods or netting. Before it is placed in the furnace, the form must be completely dried with no trace of water remaining. Pre-prepared pieces of cold glass are placed in the dry mould, which is then heated for a long period (days, sometimes weeks or even months) until the glass inside begins to melt and fills all the areas inside, even the smallest crevices. In the next phase, the temperature is gradually lowered so that the hot glass inside the mould can slowly cool, stiffen, and eventually harden. Cooling the glass needs to be taken slowly to avoid internal tensions arising in the glass and then causing the object to crack. When the cooling is finished, the mould is removed and the glass, once outside of it, is usually further worked through grinding, polishing, matting, etc. 

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The technological process is highly demanding and expensive, requiring great experience and practice from the artist, since each sculpted shape, or each type or colour of glass, reacts differently, so that the timeframe and procedure for melting and cooling has to be set individually for each casting. The first artists to use this method were Stanislav Libenský and Jaroslava Brychtová for their designs of large glass objects installed as architectural elements. It was, in fact, Jaroslava Brychtová who in 1954 created a specialised workshop, entitled “Glass in Architecture”, as an expert division of the Železnobrodské sklo glassworks. Located in the village of Pelechov near Železný Brod, the workshop developed and furthered the technology described above. Since 1994, under the name of Studio Pelechov, it has been managed (and is now owned) by its chief designer Zdeněk Lhotský; in addition to the studio’s own designs, he and his team also realise on commission the designs of other glass artists. In the field of molten-glass sculpture, Czech artists and designers are among the world’s best, with several of them moulding the objects in their own studios. ​