Honestly, the EHBP-01 is small and light enough to be slid around quite easily. If you really want casters, you can mount them up inside the base framing at the extreme edges. Depending on the side casters you use, you may or may not need a small 3/4″ mounting plate to help extend them down far enough. Remember too, casters will add to the height of the bar…if they extend an inch, it is suggested you trim the vertical support parts by 1 inch too.
[attachment=105]EHBP-01Casters.jpg[/attachment]
Note: The front foot rest gap is rather narrow for a 3″ caster, so either extend the base side frames to allow for a larger gap and use a 2×8 (or 1×8 hardwood if you prefer) for the foot rest top or use 2″ caster and use an offset plate (scrap 1×4 or similar) so they reach the floor.