If you are hanging a sign, you'll need 1 or 2 anchor points. Pick up some large, plastic, screw type wall anchors. (They are the type used for drywall) and some eye-screws about the same size as the metal screws that come with the anchors.
1.) Screw the eye-screws into the plastic anchor.
2.) Screw the plastic anchor into the styrofoam.
3.) Unscrew the plastic anchor out and dip it in water, (because Gorilla Glue needs moisture to work)
4.) Put a drop of Gorilla Glue in the hole and,
5.) Screw the anchor back into the into the hole.
6.) Wait until the glue hardens then hang with fishing line or whatever.
After I made the last propeller I found an easier and faster way of making it. This way saves a lot of sanding and shaping.
It ended up looking like this.
I took three paint cans, one gallon, one quart and one pint. I traced around them onto a piece of 2" thick styrofoam.
I cut them out and glued them together with Gorilla Glue.
Then I took a 3/4 inch paddle bit and shoved it down into the center of the biggest circle. The paddle bit keeps the styro from stopping and makes it easier to sand.
Then I hooked it up to my drill press. If you don't have a drill press don't worry you can just clamp your regular drill to the side of a table or something so it would be stable. I don't really think that it makes a difference if it is going up or down.
Next I turned the drill press on and used a piece of 80 grit sandpaper and sanded it down. The paddle bit keeps the styro from spinning around the middle while it is being sanded, and the smaller circles mean you don't have to sand so much.
I also cut some grooves in the nose once I had it sanded smooth. I just folded the sandpaper with the grit side out, and stuck the folded sandpaper into the styro and left it there. It carved a perfect groove without me having to struggle with it.
After I got it shaped into the cone, I glued it to the propeller so it looks like this
I have been asked to make a styrofoam propeller for a VBS. They want to paint it themselves so I just have to make it.
I started by drawing off a pattern on paper mill paper. It is about 4 feet long from tip to tip. I cut it out a little big with the heat knife. The heat knife tends to melt a little farther than you really want it. (In the past I have used an electric knife. That's right just like the one that is used only at Thanksgiving to carve the turkey. It works well for cutting styrofoam.) I want a very clean edge because I am going to shape it.
I also cut out 3 circles. (I know only there are only two here. I can count ok? I just didn't take a picture of the third circle.)
I cut out the shape on the band saw. I took my time because one small bump can make a huge cut in the wrong spot.
I stacked the circles, one on the bottom, and two on the top. It has to be away from the wall a little. These two on top will be shaped into a cone.
I glued the circles with gorilla glue. This glue does not eat foam and it bonds extremely well. Just be careful not to put too much glue. The glue doesn't sand as well or as fast as the styro so learn from my mistakes and don't use too much.
I put glue on all the pieces not realizing that I didn't need it on the top one. So the top circle got twice the glue that it needed.
One thing about Gorilla Glue is that it needs moisture to work, so I sprinkled some water on it before I put them together. I was going to use my spray water bottle but I couldn't find it.
I clamped it together and waited.
Then I used my sander to shape it. Yes you can sand styrofoam.
I did the same for the other side and formed the nose into a cone.
I am going to ask them to take a picture of the final product so I can post it here.