How many pieces at a time can fit into the MagicFuse microwave kiln?

It depends on the microwave oven you are using. The heat distribution in some of the inexpensive ovens is poor. This limits the firing to a single piece of glass unless you don't mind having full-fuse and medium-fuse pieces in the same firing. Better microwave ovens can evenly fire about four glass pendants per kiln load. You can compensate for uneven firing by using the turn table in the microwave. But the less expensive ovens fire unevenly even with the turn table. Reducing the power setting can improve heat distribution because it increases the number of turn table revolutions during the critical last 30 seconds of fusing.