The timber used was Pine. Total cost was $60.00
Marking out the dowel holes in the end frames requires accuracy, so measure twice drill once.
I found it easier to drill the frames in pairs clamped together.
The shelves are two pieces of 140 x 19 mm Pine biscuit joined together then ripped down to a width of 242mm.
The trenches routed across the underside of each shelf allow the dowel to sit in them and lock in position.
The shelf stiffener needs to be screwed onto the shelf back when in position at time of original assemble then the end frames just clip on & off when you need to move it around.