Well, as a little side-project from painting little miniatures, I thought I'd try to turn my hand to a diorama. As my "army" so far consists of Dwarves, and I got some ideas from a gaming-table in a Games Workshop in Oxford Street, I thought I'd create a mountain fortress for my Dwarven Cannon.
I've created a little record of this, my first, valiant attempt...
Getting Ready

To start with, what do I think I'll find useful to get going? Well, some tools of course. Nothing too fancy, a couple of pairs of pliers, a craft-knife sharp enough to trim a good chunk of flesh off a finger (allegedly), a good sharp pair of scissors, a pencil, a couple of brushes and a trusty assistant, in this case one of my cannon-I suppose might be a little less common
The vernier-callipers are one item that I suppose might not be so common to many people, but I've owned a pair for years and find them extremely useful. Uses range from simply being able to "lock" a measurement such as the height of a row of bricks, marking consistent distances into something, or using the depth-gauge integrated into the end of it to stop me digging out of the back of a model by mistake.
I also use a few other bits and pieces (not shown), such as a pair of tweezers, a generous quantity of PVA glue, water, and a set of acrylic paints, in my case Citadel.
For the actual construction, I'll be using some random pieces of polystyrene that used to be packaging for an old toy of some sort and a sheet of card. No idea what weight the card is, but it's about 1.5mm thick. The card I bought from a craft-shop, but I guess any old card will do - we're going to be painting everything anyway.
The Form Takes Shape

Well, this ugly little contraption is the start of it all. The polystyrene packaging I had lying around had some convenient shapes to it, and I then used the knife to (oh-so-carefully) chop and hack bits of it away to get a kind of shape I liked the look of.
This is the first point at which I started getting an idea of the final form - when working with pre-formed bits you're kind of limited to the medium a little bit. If you're using foam of some sort, you can of course carve any shapes you like.
I then used super-glue to start sticking bits together. When this caused my polystyrene to pop and fizzle into a sticky mess, I hastily reverted to the trusty PVA glue instead. It takes a lot longer to dry of course, so I taped the whole thing up with some electrical tape I had lying about. Anything less sticky than full-on Sellotape should be fine, so use masking tape for example. (Standard sticky-tape could be so stick as to leave tracks when you pull it off the polystyrene later.)
Once I'd decided which parts of my model would be stone walls, which would be virgin rock, and which paved, I used a brush to mark out some areas with a black-ink wash. This was really more to help visualise what was going to go where than any actual contribution to the final appearance, but getting some paint on the polystyrene at this stage should help prevent white spots later on.
One other thing I did before continuing with the construction is to use some Milliput (like Green Stuff) to fill in some of the joins in the polystyrene. This will probably need refining (or more likely digging out again) later, but I thought it might be worth getting rid of some of the more obvious artefacts.
The Bricklayers Arrive
Well, I hear that Dwarves prefer metal to anything else, but there are a few that can turn their hand to masonry, and they soon turned up at the scene.
I now cut a few strips of card, about 12mm or so wide, and then chop those up into what I hope will look like large stone blocks. I just nip the corners off too, to make a bit of space for mortar or something. In hindsight, this last step might have been a mistake, as the closer-fitting brickwork I build later looks better. Perhaps the big walls were build by Orcs or something - Dwarves would be much neater.
I start to glue the bricks onto the where the walls will be, using a fairly predictable "brick wall" arrangement. In this case I carry the pattern all the way around the back of the model, although if you're going to be mounting it in a display-case it might be okay to miss out some of the detail around the back.
There wasn't a huge amount of genius involved here, I just created a pile of bricks the same size, and stuck them on one-by-one all around the model. I used bricks about 1½ times longer than normal for the corners, to represent the fact that you're seeing two sides of the same brick here.
A small note is that the PVA glue I'm using here is always watered down about 5:1, which makes it a lot easier to evenly apply with a brush.
Carry the Cannon Up The Stairs?

For some odd reason even my Slayers refused to carry a large cannon up some old steps carved into the mountain. What was called for here is a doorway leading to the grand interior of the Dwarven fortress buried in the mountain.
I used the Scalpel Of Finger Slaying to cut the outline of a doorway into the recessed part of the model, making sure not to cut right through the beautiful brickwork at the back. Another point of note here is that when cutting polystyrene, especially the type used in packaging (With the ~5mm pea-sized particles), is that if you cut with a simple single-stroked slashing motion, you'll most likely end up just pulling out chunks of polystyrene. Use a very short-stroke sawing or stabbing motion to ensure a nice smooth cut.
Once I had an outline of the doorway, I used a pair of tweezers and a pointed file to pick out the bits of polystyrene I wanted removed. The cellular nature of the poly made this pretty easy.
The next few stages were really just to fill in the gaps of my impatience, as you can see I didn't finish the bricks before starting on the door...
I finished the rows of bricks all the way around, and also painted the "interior" of the doorway black.
Call that a wall?

The doorway looks a little sad there, all plain and unadorned, so I called in some proper skilled Dwarven masons this time, instead of the lazy fools that build the big walls.
I made a card template to fit the gap nicely - the callipers help immensely here for measuring awkward gaps - and then cut much smaller strips of card for course of smaller bricks. These I stuck onto the card template, which makes it much easier to get a neat finish than if you're trying to stick individual bricks onto polystyrene.
On top of these bricks, I then stuck some slightly rounded pieces to indicate an arch and keystone.
The whole arrangement could then be slotted neatly into the gap.

Off the Rails
Of course the poor Dwarves can't be expected to push a big heavy cannon towards a precipice like this unassisted, so they built a track for it to roll along on.
For this I used a short section of standard Hornby rail track, which seems to be almost a perfect size for the wheels of my cannon. I spruced it up a little bit, so using a layer of Tin Bitz paint over all the brackets and sleepers (Dwarves aren't going to use wood, are they!), followed by some Burnished Gold for the fittings. This made the track look nicely metallic. I also re-painted the rails in something silvery (Mithril I think) as they'd been sitting in my shed for about 20 years (damn, that hurt to write down!) and so had lost a bit of their shine.

~~Interlude~~
That's all I've done so far. Check back soon
tm for the next instalment...