Yes, we can mark this down as another use for duct tape!
Before we go any further, I need to address some safety concerns. You need to be very comfortable with fire, and have an environment where you can use open flame. Sandblasters are very messy and you need to be prepared. Also, a well grounded knowledge of woodworking is not necessary, but will come in handy. I will try to fill in any gaps in how to work with the wood where I think it is unique to this project.
Materials you will need:
Hardwood boards glued into panel (size is up to you, but you should have it rather thick). I chose 2" thick rough cut hard maple. It will work better if you use a closed grained wood (no open pores).
Metallic tape, usually used in automotive applications
Sandblaster and relevant equipment i.e. mask, gloves, sand
MAPP gas torch
Small butane torch
Xylene or other solvent
Scotchbrite pads/steel wool 0000
Artwork, either full size or to scale with gridlines
Step 1: Make your artwork and transfer it to your sign.
Cover the entire front side of the board with one layer of duct tape followed by one layer of the metallic tape and then another layer of duct tape. You only have to cover the area you will be doing your artwork with all three layers, but to be on the safe side, cover more than you'll need. Better to have too much and be protected than to find out later that you don't have enough layers and your wood burns.
Make your artwork. Either draw it directly on the board or use a computer. I used a computer and used a font that was inherently irregular. This helped with any oopses I had during the process. Transfer your artwork to the board. If you only have a scale drawing, as I did, you'll have to grid out the drawing and the board. Then it is only a matter of sketching the artwork using the grid as a guide. I used ViaCAD Pro to make the grid on the artwork. This way I was able to make 1" squares to scale very easily.
When working with grids, it is important to have a system with which you can have the grids in exact proportions to each other. To grid in ViaCAD Pro, you need to open the artwork in a 2D project and set your dimensions to match your sign. You can then draw the horizontal and vertical lines by "snapping" them to the workplane grid. It works best with 1" squares. Using the computer program saves you from doing some math!! I've done it with other pieces and I know from experience, the computer is the way to go! However, you can also do it without the computer by using a ruler on your scaled copy and figuring out the right size to make your small squares to match with your larger squares. For instance, if you make your small squares 1/4" to match with your larger 1" squares, you will have a sign that is 4 times larger than your piece of paper. If your paper is 8.5" x 11", then your sign will be 34" x 44".
Lay out your grid on your tape covered sign using the T-square, ruler and the Sharpie. You should have 1" squares. If your sign is not exactly square, you will find out in this step. If this happens, just choose a side to call "normal" and work from there. Just make a mental note to trim your sign at the end (before varnishing). If you end up trimming, use a straight edge guide and a circular saw. To keep the saw from leaving marks where it skids along the surface, just put a couple rows of painters tape on your board where the saw will slide along the straight edge.
To sketch according to the grids, just count your squares and draw the design in each square individually. This works great in breaking down a large project into more manageable pieces (1" squares to be exact).