Have you ever wanted to make a rustic large wood sign but you just don't have it in your budget or you are worried about the weight that this type of sign would have! I have your solution..... You can easily make styrofoam mimic the look of wood! That way you achieve the desired look with less cost, weight and construction. A WIN WIN WIN!!
You will need to start by buying the styrofoam most home improvement stores stock it. **here is a clue when searching for it (otherwise you will be lost and when you ask for styrofoam people look at you like your crazy) the intended use styrofoam is insulation! The type we purchase come in 4ft X 8ft sheets and they are sold at different thicknesses they range in price from $8-$20 per sheet. They also sell a smaller 2ft X 2ft version (I believe) it seemed a little denser but it was more pricey. I'd rather have a whole sheet with left over then more density. Be prepared when you purchase (and learn from our mistakes) they are huge and awkward to put in your vehicle, the first couple times we tried to awkwardly tie them down and now we have realized that most of the time if you put some weight on the top of them they won't go anywhere!
Now the fun begins!
First you want to map out the size of the sign you want, I'm my case I wanted a 5ft tall sign by 2 1/2 ft wide, you can then cut that down.
This process is a lot easier if you have a heat knife, but would work with a regular knife or razor blade. You achieve much cleaner edges with a heat knife and it is much easier to paint when they are smooth. The one we use is owned by the church we do VBS for, they bought it for VBS because so many of our elements are made from styrofoam. The one we use is an industrial tool but you can buy something less intense and can be bought at michael's or another craft stores.
This thing is a game changer though, you just pull the trigger and it heats the blade and it then slides through the styro like butter! It was an investment for them but I think it is worth it if you plan on doing large scale projects.
So after I had the basic size I then decided the width of the boards since it was (2 1/2ft) 30 inches wide I decided 10 inch planks would be perfect! It doesn't have to be perfect but even is better then having completely random boards unless that's the look your going for. Another handy thing with the styro is there are hash mark with measurement indicators so you can cut along those lines, as a matter of fact I think that's how I decided my board width (5 hashlines) I can't be bothered with a tape measurer, ain't nobody got time for that...
I then just made a v type of shape indentation along the length of the board, making sure to not cut all the way though the styro. Your basically wanting to give the boards "separation" while still being connected. The ends is where you can cut in and give a more board like appearance notching a true division so they look like boards.
I also added some gashes to make some knot looking things in the wood, I made them diamond shaped following with the "grain" of the wood.
The next step is to add the first layer of brown to the wood, I used a reddish brown color. I didn't take a picture of that step because I immediately went and grabbed a darker color to tone down the red in the brown color (I wasn't feeling that red). Also working quickly made it easier to blend the colors together, wood doesn't have sharp edges so you want a smooth transition. You want to pick the direction of your grain and keep the paint following in that direction. Also make sure to focus the darker colors along the edges and in the deep grooves.
I moved on to a darker almost black color, and really intensify those grooves.
Adding the black makes it really pop and the boards really look like boards, you want to make sure to deepen those knots with black so that it gives them dimension.
We made this particular sign for Vacation Bible School decorations so I then painted an image on the sign to match the decor of VBS.
Excuse the hideous outfit but as you can tell this type of sign is extremely light, ideal for VBS decorations.
I hope this helped you in your transformation of styrofoam to wood!