Need to know wattage, inputs (115V or 115V/230V), Outputs. Do you want a switching supply (most likely to find in a low profile) or a linear regulated?
Designed a 3-output linear regulated 1U once. Used a torroid xfmr, and some real short electrolytics.
A 1U height is not an easy task. Many small switchers are not enclosed, so you have to consider clearance to the top, and how to insulate.