WHAT YOU'LL NEED
Aside from whatever paint & flock you'll be using, you'll also need:
- A bunch of tongue depressors (these ones are roughly 6" x ¾" in size).
- PVA glue (this bottle cost a £1 from the local Poundland store)
- Cheap fish tank gravel (this 1.75kg bag cost £2 from a local pet store)
- Cheap wall filler (this tub comes ready-mixed, and costs a mere £1 at Poundland).
Trim the rounded edges off one tongue depressor, and glue it to the centre of another (I used superglue for this, but hot-glue or similar will also do the job).
After washing a cup full of gravel (and leaving it out in the sun to dry), start gluing some of the bits of gravel to the tongue depressor with the PVA glue.
EDIT: see the comments for warping issues.
Once you're finished gluing all the gravel in place (in a kind of jigsaw fashion - so that it all fits together reasonably well), leave it to dry overnight.
Fill in the cracks with some of the wall filler (in a similar way that you would grout bathroom/kitchen tiles),
STEP FIVE (optional)
Simply paint the wall (though you can just leave it as it is if you prefer), and apply some flock to the base.
And that's all there is to it :)