My biggest project to date - the ultimate sandpit - it has built in seats that fold to cover the sand when not in use and prevents it from becoming what would otherwise be the litter tray for every neighbourhood cat.

This is a time consuming build but well worth it - there's lots of timber to buy, cut, paint and assemble

Step 1: Cut, Cut, Cut and Paint

You'll need to cut and paint a lot of timber; all wood should be treated for outdoor/landscaping use
Except for the sleepers and base decking it all needs to be painted. It is far easier to paint the components prior to assembly

Cutting list:
3 sleepers – 200 x 50 x 1662mm (base)
17 decking boards – 90 x 22 x 1469mm (base decking)
12 side battens – 90 x 45 x 264mm
4 side lengths (A) 90 x 22 x 1620mm
4 side lengths (B) 90 x 22 x 1470mm
18 decking boards – 90 x 22 x 1600mm (lid decking)
4 backrest supports – 90 x 45 x 590mm
4 seat battens – 90 x 45 x 290mm

Step 2: Make the Base

Lay out the three sleepers on a flat surface evenly spaced using one of the decking boards as a guide for positioning to final length. Then screw down the 17 decking boards spaced approximately 3mm apart

Step 3: Make the Sides

Take 8 side batten pieces and butt join to make the corner braces and screw them to the base section. You can then add the side pieces (a and B) which are each braced in the middle with a side batten length. Screw the sides to the corner braces. At this point the sandpit will merely be enormously heavy rather than essentially unmovable. Now is a good time to get it into its intended position in the yard.

Step 4: Line With Weed Matting

I didn't get a good photo of this step (the picture taken is fairly late in the construction process) but it is pretty easy/self explanatory - line the base and sides with weedmat using a staple gun. This keeps the sand in place but allows for drainage of rainwater, toddler wee etc

Step 5: Lid / Seating

Use the lid decking boards - at one end screw down three boards. Layout the next three boards which are joined on the underside with a seat batten at each end. Join these new sections with hinges so that they can fold backwards into a seat. Finally the last decking boards are joined to the backrest supports and hinged from the underside. Repeat process on the other side to make the two integrated bench seats.