A direct molding method for creating a homogeneous, polymer microfluidic channel is presented. By utilizing capillary rise and subsequent absorption of poly(methyl methacrylate) (PMMA) solution into a solvent-permeable poly(dimethyl siloxane) (PDMS) mold, various circular or elliptic polymer microchannels were fabricated without channel bonding and additional surface modification processes. In addition, the channel diameter was tunable from several micrometres to several hundreds of micrometres by controlling concentration and initial amount of polymer solution for a given PDMS mold geometry. The molded PMMA channels were used for two applications: blocking absorption of Rhodamine B dye and constructing artificial endothelial cell-cultured capillaries. It was observed that the molded PMMA channels effectively prevented absorption and diffusion of Rhodamine molecules over 5 h time span, demonstrating approximately 40 times higher blocking efficiency as compared to porous PDMS channels. Also, calf pulmonary artery endothelial cells (CPAEs) adhered, spread, and proliferated uniformly within the molded microchannels to form near confluency within 3 days and remained viable at day 6 without notable cell death, suggesting high biocompatibility and possibility for emulating in vivo-like three-dimensional architecture of blood vessels.