We've designed our planters in two different sizes – 600mm and 300mm wide. The lengths of 84mm x 19mm blackwood decking timber for both are listed below.
You can either get the 600mm timber pre-cut at Bunnings, or for the 300mm option just measure and mark the pieces and cut them with a drop saw. Label each piece and put them in their groups, so you remember where they go.
Keep at least eight off-cuts to use as spacers.
Prepare your workbench by clamping a 750mm wooden block along the back to use as a square. Lay the three pieces of timber for the front of the planter horizontally on the work bench. Place your 10mm plastic packers in between these horizontal pieces to make sure they are spaced evenly apart. Then place two internal pieces over the top, 300mm apart. Place two spacers against the wooden block at each end of your vertical pieces. Square up the horizontal pieces with another piece of wood.
Apply PVA wood glue to the horizontal pieces of timber, to attach the vertical piece. Put the vertical pieces of timber in place. Use the nail gun to secure the vertical pieces to the horizontal pieces of timber. Mark where the top of each panel is after you have finished them. Repeat the above steps to build the second front for the planter.
To build the first side panel, just follow the same process as before. The only difference is in the spacing between the internal timber blocks, which'll need to be closer together. Repeat this process to build the other side panels and base.
Apply wood glue to the vertical blocks where they will be joined to the side panel. Put the side panel in place and use the nail gun to secure the panels together. Repeat this process until all the sides are attached.
Once the front and sides have been secured, turn the planter over. Apply glue around the edges of the planter and put the base into position. Use the nail gun to secure the base to the front and sides of the planter.