A system for forming a multiple layer object, the system including: a spreader to form a layer of polymer particles, the polymer particles having a melting temperature (Tm) of at least 250° C.; a fluid ejection head to selectively deposit a first fusing agent on a first portion of the layer and selectively deposit a second fusing agent on a second portion of the layer, wherein the fluid ejection head does not deposit the fusing agent on a third portion of the layer; and a heat source to heat the first portion and second portion, wherein the first portion is part of the multiple layer object and the second portion is not part of the multiple layer object and the second portion raises a temperature of polymer particles in a subsequent layer.