This was made as I had no use for the shelf and is easy enough to make from scratch.
What you will need
Pine (enough to make a 400mm x 300mm rectangle)
Pine (2x2 Posts, 370mm in length x4)
Pine (2x1 pieces, 150mm in length x4, 270mm in length x2)
Wall filler (multi purpose)
Saw (recommended tenon and table saw)
2-4 G clamps
How to do this project
Cut timber to lengths and glue the 400x300 top together. Sand all the pieces to a smooth finish to make it easier in the future.
Get the posts and glue them to the underside of the top an inch in each side.
Get the 2x1 timber lengths glue them in the spaces on the under side in between the legs, and the two at the bottom.
Once the glue has dried, screw in a screw in each post to connect all the legs to reinforce it.
Get the filler and fill all gaps and the screw ends to give it an illusion that its all a solid piece.
Paint all the wood and sides, except the top (use tape to get a perfect straight edge for the top, check the picture).
Apply more coats (depending on the quality of paint, until you can't see the wood underneath) and use oil on the top part of the stool to give a natural finish).