A set of plastic lifts are placed between sheet pans or trays in order to stack them within an oven and during cooling and transport. The dimensions of the plastic lifts are selected to provide adequate tray spacing for circulation of air between the trays for cooking and cooling purposes. Preferably, the plastic lifts comprise a set of four cylindrical lifts of 2½″ height and eight cylindrical lifts of 1¼″ height, with two of the smaller lifts nested within an axial bore of each of the larger lifts. The lifts are fabricated of a non-slide plastic material able to withstand temperatures up to 400° F. and capable of rapid cooling. The primary object is to achieve greater efficiency in domestic and commercial food preparation by heating and transporting multiple trays at the same time and enabling a more compact footprint for the trays.