A method for manufacturing a midsole of an article of footwear includes generating a positive model of a midsole. The positive model includes a region of empty volume that defines an aperture or channel. The method further includes creating a negative model based on the positive model, and printing, layer by layer, a negative mold to form a physical representation of the negative model. The negative mold includes a region of solid volume that corresponds with the region of empty volume in the positive model. The method further includes supplying a midsole material to the negative mold to form the midsole. The midsole includes a midsole aperture or channel formed therein by the region of solid volume in the negative mold.