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This particular type uses the following materials:
- 3/16" or 1/4" thick foamcore
- 1/16" thick cereal box/thin card
- Plastic embroidery mesh AKA "granny grating" - any density
- PVA/White glue
- Cyanoacrylate glue/Superglue
- 1/4" styrene L-channel
- Basing material of your choice (sand, misc. bits, etc.)
- Exacto knife
- Box cutter/Craft knife
- Cutting mat
- Hot glue gun (will be used in future constructions)
First, cut your foamcore to a size that seems about right for your needs. My SketchUp example shows a 2 1/2" x 12" piece as a base. Make your cuts as square as possible.
Next, cut a piece of granny grating to the same dimensions as your foamcore base, perhaps a tad smaller if needed. Take your white glue and coat the foamcore's top, and set your grating on top, being sure to press it into the glue. I often use superglue at this point to "tack weld" the grating to the foamcore, then set it under a few books or magazines to insure even pressure while the glue dries. It is also good to omake these in batches, as the glue-drying phase can take some time.
The next step is to cut some card to cover the long exposed edges of foamcore so they don't react adversely to spraypainting. Cut them to the same length as the foamcore, and wide enough to end up flush with the top of the granny grating, then white glue them to the long sides of the foamcore.
Now you'll get a piece of 1/4" L-shaped styrene channel (I use Evergreen products as they are readily available in town), and cut two pieces, each equal in length to the foamcore plus the pieces of card to each side ( foamcore width + about 1/8"). Coat the exposed foamcore in white glue and score the styrene in a cross hatch pattern, then superglue them to the white glue-coated foamcore. Hold them in place while the superglue sets, then get ready for more card cutting.
Cut two pieces of card to strips, measuring 1/4" by 12" (or whatever length your catwalk is. You'll then use white glue and superglue "tack welds" to secure these to the top of the granny grating, so that you create the long sides of a "frame" over top of the mesh. See the example pic to clarify:
Next cut two more strips of card, this time 1/4" wide and long enough to finish the "frame" (in this case 2-1/16" long) around the mesh. Again, the example picture will help to clear up confusion:
And there you have it! Add basing materials like sand or pieces of discarded gear to your catwalk, or leave them clear of debris (you obsessive clean freak, you!). I've also done heavily damaged catwalks partially destroyed by explosions, using bits of paper clip stuck into the foamcore to represent reinforcement bars, and I am toying with adding pipe and conduit to new pieces to add variety.
The great thing about these catwalks is their ability to span pretty impressive distances without needing a whole lot in the way of reinforcement. The foamcore creates a sturdy base and all the card strips and such help to build up that strength. One thing I would recommend is that if you go a whole lot further than 12" in length, is to add bits that suggest structural upgrades, even if they aren't practically necessary. It adds many things: aesthetic detail, a bit of cover, and a sense of character that can become quite impressive.
So anyway, that's one variant of my catwalks, I'll look at posting the "tiled" version soonish, if I don't get distracted or think of a better idea. Please let me know if this was helpful and if there are other ideas or things I can improve upon. I'll try to get actual WIP shots when next I build something, so I don't have to point to a screenshot.
Cheers, and good luck trying your hand at some new catwalks!