An electrophoresis microgel is formed in a gel holder. The gel holder comprises a top substrate, a bottom substrate and a spacer disposed between the top substrate and the bottom substrate. The spacer establishes a separation of from 25 to 250 microns between the top substrate and the bottom substrate. A gel compartment is formed by partially sealing the top substrate to the bottom substrate, while leaving an opening for the introduction of unpolymerized gel. The gel compartment is then filled with an unpolymerized gel, which is polymerized in the gel compartment. Electrodes may be printed on the substrates, may be contacts to an exposed edge of gel, or may be applied through windows cut into one of the substrates. One type of gel holder makes use of graded beads having a diameter of 25 to 250 microns slurried in an adhesive such as an acrylate adhesive as the spacer. The slurry is printed onto the surface of one or both substrates to form a spacer of the desired shape, and then hardened using heat or light. If desired, the spacer can establish lanes within the gel.