You need:
Clean Soft Body/Acrylic Gouache pots
Wooden board
Clear Gesso
Craft knife
Wood screws and screwdriver
Plus a drill OR strong adhesive OR Velcro patches to fix

Prepare your wooden board with a coat of Clear Gesso. This will allow you to wipe down paint spills and protect the board from water damage.

Use a craft knife to cut all but one of the pots to your preferred size. Make sure you've removed the label and cleaned them first as these are going to become your new paint holders. Keep the uncut pot to the side, as this will eventually be your brush or water holder.

Place the cut pots on your board in the positions you want; remember to leave spaces for mixing pots and brush holder

If you are fixing your pots with screws, drill through the bases into to the wooden board.

Tighten the screws with a screwdriver. Alternatively, use strong adhesive or Velcro to fix your pots to the board. Velcro will allow you to remove the pots to wash them out but won't be as firm a grip to the board. 

Fix the clean pot lids on to the board - these can act as mixing surfaces. Glue or screw them where you want them.

Take the pot you've saved as a brush/water holder, and drill a hole in the bottom if using screws to fix it.

Screw it in place on the board using a screwdriver.

If using Velcro strips, you'll be able to move your pots as needed - handy for washing out.

Fill with paints and start using. Your upcycled palette is complete!