I just discovered (few years ago now - Dave) that the inside of a 3 1/2" floppy disk make rather good wall/bulkhead textures. Here is the main gist of it ...
Take a disk (preferably one that is no good), break it open, and rip out the magnetic disk, and padding. Cut 1/2" off the bottom (the end that goes in the drive 1st) of both halves. Glue the halves back together inside out, with two bits of card between (I used a piece of a Lictor package) with some of the card protruding beyond the end of the disks. This will be used to attach the bulkhead, or as a stand if its a free standing barricade/wall. Paint appropriately! The 1/2" thats left over makes a good barricade if made the same way.
The more busted disks the merrier. I glued two halves with the hole in the centre together to form a kind of window, and another section has a large pipe (conduit elbow) exiting it into the ground. I've got a billion ideas/uses for this, just not enough wrecked disks :)
A good way to make craters is to get various sized jar lids, say from mustard, mayonnaise, pickle jars, etc. Put it on a table and lay a piece of aluminum foil on top about an inch larger in radius than the lid you are using. Push down on the foil both inside and outside of the lid, then pinch the foil around the lip of the lid. This will create a good looking circular mound around the crater. While holding the foil in place flatten the outside of the foil flat on the table. Remove the foil from the jar lid and glue the outside flat are as well as the middle of the crater onto a base. Paint black, drybrush in layers of brown and flock around the outside edge to cover the join between foil and base. The crinkled foil itself makes a good exploded earth texture, but sand an gravel and even bits and pieces of destroyed junk make them really stand out. Fast and easy and cheap!
(Polyfilla is a brand name for wall filler - the stuff you mix with water and fill cracks in walls with. I believe the Americans call it spackle - Gary)
Especially for all you foamcore (AKA foamcard) users out there...
After completing your buildings, you are usually left with some strips of foamcard which, until now had no use. Now, you can use them to make some quick and cheap craters.
Cut the strips into triangles and glue them into a circle on some (fairly strong) card. Glue the triangles down by the LONGEST edge as this will result in a slope both inside and outside the crater. It's a good idea to try out the circle before you glue it down as this lets you get a natural look.
Leave to dry completely.
SLIGHTLY thin some Polyfilla and add a fairly large helping of brown ink to make a "mud" colour. Paint the mixture over the whole circle, including the centre using a thick old paintbrush. If your mixture is the right thickness, it will fill the gaps and stay in position, but will still be easy to apply. Trim the outside of the card so that it's about 1cm from the edge of the crater.
Have a beer and admire your handiwork.(I like this bit...Gary)
I really mean it about the beer...(so do I...)
Cutting the triangles roughly mean that the edge of the crater is rough. Exactly what you want...
The bigger the triangles, the bigger the circle you should make, so you can make different sized craters.
These are easiest to do in groups of 5 to 10.
The brown ink means that the craters are ready to use as soon as they dry, and makes it easy to see where you have and haven't filled. You can paint them up carefully later if you like...
I generally leave the circles to dry for 24 hours before adding the polyfilla.
For your question about sandbags - I have found a really easy and realistic way to make them is to use medical gauze dipped in Elmer's glue (White glue, PVA glue - Gary) left to dry overnight, primed with black and drybrushed with Snakebite Leather, slowly building it up with more white mixed in after each dry brush. Dipping the gauze in a mixture of Flesh Wash, water, and Chestnut Wash also seems to work well. The gauze needs to be cut about 1/2 to 3/4 of an inch wide and rolled up, dipped in thinned down Elmer's glue and left to dry overnight. It is fairly easy to add this to a tank and molds into shapes fairly easily.
Gary: As for the question about making sandbag walls I think Fred's approach is the answer. To make a sandbag emplacement I would try making a wall out of air-drying clay and covering it with gauze to get the sandbag effect. Try this: Take some air-drying clay (DAS, Efaplas etc) and roll it into a long sausage about, what, 6 to 7 mm thick I guess. Chop it up into little sandbag sized portions, and pile them up to make your wall. I imagine that chopping the sausage up will flatten the ends just like sacks or sandbags. Now, either cover the wall with gauze and watered down PVA, pushing it well into the cracks while it is wet, or just press the gauze onto the soft clay wall to make a pattern in the surface. Let me know if anyone tries this out eh?
Tibor comments: Well, I use real miniature sandbags (by Italieri, I think), but that would be not in the spirit of the Terragenesis site. So I tried making the sandbags from the reader's tips section. After some experimenting (and a few metres of gauze) here is what I found out: Make the clay sausage, just as you suggested, but before cutting it into smaller pieces, flatten it a bit. After cutting, the edges I got were unnaturally sharp, so they needed some rounding as well. Then I rolled each of these small sandbags into two layers of gauze (the one I got had relatively large holes in it), soaked it in PVA. After painting them I assembled the wall. It looks quite nice. (Though the ends of the nags are not hanging down that much.) However, for the "real sandbag effect" you have to sew some tiny bags, and fill them with sand... :)
Gareth is something of a celebrity at my gaming club, having been in White Dwarf showcasing his armies more than once. He is also an accomplished terrain builder and I hope to feature some of his work soon. An industrial piece he recently brought in had some nicely textured floor plates which turned out to be the packing band that comes around the Games Workshop boxes - you know, that very tough plastic banding that is about 10mm wide. It has a nice diamond pattern texture to it. Cut it into strips, glue it to your floors, spray it black and dry-brush with silver. I have also seen cross-stitch canvas used to good effect. This is the material with the square cross-pattern on it that is used when making tapestry pictures and so on.
Two readers sent me recipes for sludge on, for example, chemical plants. AJ Karp suggests mixing green (or whatever) colour paint with flour to get instant lumpy sludge that sticks to walls. Scarekrow suggests using PVA glue which you first allow to set until it forms a skin. Then add a few drops of superglue, which caused a reaction on the surface to give a lumpy, sludgy effect. I have also used hot glue guns for sludge oozing from pipes, as you can see in the giant pipes section.
Take 15 pennies or as many as you feel necessary. Wrap them in black electrical tape making sure you have a little bit above the pennies. Use one of the sludge recipes to add sludge to the top of the barrels.