Step 1: What you will need
stencils (if you want precise letters)
ex-acto or razor knife with sharp blades
various shades of acrylic paint (brown, tan, white, black, gray)
Step 2: Letter your board
Step 3: Begin to carve the letters
always angle your cuts toward the center of each letter/symbol. that way the letters will pretty much pop out easily with a flick of the finger.
using the sharp blade, also cut long, meandering strips across the sheet. this simulates the woodgraining that a plank has. also 'notch' the edges to add more realism to your board.
Step 4: The heat is on!
DO NOT hold the gun still. keep it moving, sweeping across the sheet. if you hold it still, it will burn through and ruin your hard work!
Step 5: Coloring the board
don't try to do the woodgraining at this point.