This is a post-and-apron frame on four locking castors, carrying two plywood shelves. The top one gets a low rail around three sides to keep bottles and glasses from sliding off in transit; the bottom one is left open for whatever needs moving. Nothing about the joinery is fussy — it is glued and screwed apron frames, sized to a half-sheet of plywood so there is almost nothing left over.

A Pine and Plywood Rolling Bar Cart

What you need

1 length 3.0m length of 44 x 44mm PAR softwood legs — cut into four 680mm lengths
2 length 1.5m lengths of 19 x 44mm PAR softwood aprons — cut into four 412mm and four 262mm rails
1 sheet 600 x 1200 x 12mm birch-faced plywood two shelf panels, 412 x 262mm each
1 length 1.2m length of 20 x 6mm hardwood half-round moulding gallery rail on three sides of the top shelf only
4 50mm locking swivel castors with mounting plates rated at least 30kg each; rubber-tyred, not hard plastic
1 box 40mm countersunk wood screws
1 box 25mm panel pins for the gallery rail
1 wood glue
1 tin food-safe hardwax oil for the shelf surfaces

Step by step

Cut the four legs to 680mm from the 44 x 44mm stock on the mitre saw, squaring each end.
15 min
Cut the apron rails to length: four long rails at 412mm and four short rails at 262mm, enough for a top frame and a bottom frame.
15 min
Mark the bottom frame position 80mm up from the foot of each leg, then clamp the four bottom rails to the legs dry and check the frame is square before committing to glue.
20 min
Glue and screw the bottom apron frame to the legs, pre-drilling and countersinking each rail into the leg face so it can't split.
30 min
Repeat for the top frame, flush with the top of the legs, then stand the base up and check it doesn't rock on a flat floor before the glue goes off.
30 min
Cut the two shelf panels to 412 x 262mm from the plywood sheet on the table saw, supporting the sheet so the offcut can't tip as it clears the blade.
25 min
Ease the top edges of both panels with a block plane or sanding block so they don't bite into a hand reaching over them.
15 min
Drop the shelves into the two frames and fix each one up through the apron rails from underneath, so no screw heads show on top.
20 min
Mitre the gallery rail moulding to fit three sides of the top shelf, leaving the front edge open for loading, then glue and pin it down.
30 min
Sand the whole cart through the grits, finishing at 180, and round over any sharp arrises.
30 min
Apply a first coat of hardwax oil, let it cure, then apply a second coat.
20 min
Stand the cart upside down on a blanket, mark the castor positions inset from each leg foot, and bolt the castors on, locking the two at one end.
30 min
Stand it up, load it empty, and roll it across the room before it carries anything, checking nothing racks or squeaks.
10 min

Afterwards

Let the hardwax oil cure fully — at least 24 hours, longer in a cold workshop — before loading the shelves. Wipe up spills from the gallery rail promptly so they don't sit in the corner joints and lift the finish. Once it's rolling over doorsteps and uneven floors, check the castor bolts for play every few months and retighten.

Questions

Will the castors mark a wood or vinyl floor?

Not if you buy rubber-tyred castors rather than hard plastic ones, even loaded. Hard plastic wheels can leave black scuff marks on vinyl.

Is 12mm plywood strong enough for the shelves?

Yes, for bottles and glassware over a 412 x 262mm span. If you plan to load it with cast iron or large planters, go up to 18mm ply or add a centre support rail.

Why lock only two of the four castors?

Locking the pair at one end lets the cart park square against a wall or counter without drifting, while the free pair at the other end still swivels for steering.

Can I make it taller to use as a kitchen island?

Yes — add the height to the legs rather than spacing the shelves further apart, and recheck it isn't top-heavy before loading it. Past about 850mm a loaded top shelf gets noticeably less stable on castors.