Anyone who has skills in woodworking, can also make the cold frame window yourself.
You need strong ones for this, about 60 x 40 mm thick slats. You will get a fold all around on the inside, in which the disc is inserted and fastened with weak strips. The frame has one or two channels on the lower narrow side, so that the rainwater can drain away. The slices are 73cm x 141 or 143cm tall, so that a normal window of 80 cm x 150cm in size. Weaker than 3 The glass panes must not be mm. Old apartment windows are also suitable for a small cold frame.