*PLEASE NOTE* - This tutorial will require the use of a hobby knife and pliers - please use proper safety devices such as gloves/goggles when necessary. Conduct this at your own risk. I can not be held responsible for any damage done by following this tutorial. This is simply for educational purposes.
First things first, you'll need some supplies such as the ones shown in the following picture. Super glue (I recommend Zap-A-Gap,) some PVA or Elmer's glue, sand, and miniature hobby bricks (I'm using ones from Secret Weapon in this tutorial.)
I am also going to be using the following paints in this tutorial:
Reaper Master Series:
You will also need access to black and light gray primer in order to paint the base effectively using.
Now that we've gone over the supplies we can get into the actual creation of the base. To start you will need some plasticard (sometimes called styrene) in a thickness of around 2-2.5mm. You want it to be sturdy enough to not flex under the miniature but still be able to be bent and cut out easily with an xacto type blade. You will then place your base over top of it and rough out a shape that you wish the "asphalt" level of the base to be. This will most likely need to be slightly bigger than the base itself. (In the following picture I actually made the overhang too big for my taste and cut it down to size accordingly.) Be sure to make this outline larger than you intend the actual design to be as it will allow for error when cutting/trimming the pieces. This will look something like so:
Once you have the lower level of the base traced out you will need to score the line about 2 times. I prefer to do 2 different scorings - applying light to medium pressure each time. This will be safer as it will help keep your blade from snapping or possibly sliding out and cutting you or another unwanted surface. Don't worry if you can't follow the lines exactly, you will need to trim up any sharp edges or rough spots afterwards anyways. The idea is to just follow the rough outline.
As long as you scored the plasticard enough you should be able to just use some pliers to cut into the design slightly, and then use your hands to pull the edge up around your cutout giving you a nice smooth outline. This will look something like so:
Once you have this "lower level" of the base cut out you can use it as a guide to make your second layer (in my case the "sidewalk" of the base.) You will simply use one side of the base and slide it over a flat edge of your existing plasticard to help create your guideline to cut out the sidewalk level. This will look something like so:
Once you have this second level cut out you can glue it to the bottom level using super glue. After allowing the layers to bond sufficiently you can use a knife or hobby files to match up the upper and lower levels if there is any unwanted overhang. You should now have a solid base to put the rest of the details on now:
At this point I like to dry fit some bricks onto the sidewalk or other parts of the base just to get a feel for where I'm going to want to glue things down. At this point it is also a good idea to test fit the miniature and figure out where you are going to want your "rubble" and sand piles to be as well.
Once I have thought about where I want the rubble and debris to be located I apply glue to the places and begin setting down my bricks first. Once they are in the correct spots I add more glue where I wish for the sand to be located. Think about where the little pieces may collect, specifically against the sidewalk and up against the bricks. You can also add little pockets of sand around the base to add more interest to it. It is important to note you can use PVA glue or super glue for the application of bricks and sand (in this particular instance I used super glue as I was time constrained, but the super glue can cause bad eye irritation when used in larger quantities on bases such as this, so I would caution its use here.) I have also decided to attatch the gaming base to the underside of the piece now to make it easier to hold. In the end you should have something that looks like this:
There you go, you now have a built scenic city-scape type base! You can add further details such as skulls, spent shell casings, or wires/metal bits at this time before priming if you wish. For this particular base I am leaving it with just bricks and rubble so I will now move onto priming. Begin by priming the piece with a flat black primer.
Once you the flack black primer is done drying you can lightly apply a grey primer over the base while still leaving some black showing through. This will help give you a good "concrete" or "asphalt" look to your plasticard before you begin shading/toning it.
With our "basecoat" done we can now begin shading our base. In order to differentiate the lower surface as asphalt and the higher surface as concrete I begin by applying 2 coats of Nuln Oil over the lower "asphalt" surface of the base. The first picture below is after the 1st shade had dried, and the second picture is with both layers of shade dry. Try not to apply this as a super heavy wash, you don't want massive puddles of wash covering up the stippled primer effect we built up earlier. Small puddles are ok as they will help simulate some oil or other substance that could have built up on the ground.
Once the shades have dried we can move onto tinting the rubble/bricks before we begin to further shade/highlight them. This step is important as we will be using multiple washes to help differentiate the rubble from the rest of the base. We will do this by washing all the sand and bricks with Seraphim Sepia. (You may notice my base took a little spill accidentally and a few of the bricks chipped - this was not intentional and I wouldn't suggest dropping the base unless you like the effect it added haha.)
Once this shade had dried I lightly drybrushed the sand and bricks with Ushabti Bone. I am using warmer colors such as bone to highlight my bricks and rubble as it will help to add more interest to the base that has more cooler tones in it from the black/grey currently. You can alternatively highlight with lighter grays if you prefer your base to have a more "cool" tone to it color wise. This will look like so:
From here I further highlighted the rubble and bricks with Screaming Skull - this time focusing only on the higher points of the rubble and bricks. In the second picture you can see that only the top parts of the bricks that are protruding into the air are highlighted. This is important as we will later be shading the opposite ends to create more contrast with shadows.
Now that we have our highlighting finished we can begin shading the base. I will start by applying Agrax Earthshade to all the sanded bits. The bricks will also be washed with the same color, but be sure to focus your wash onto the "opposite" sides of the bricks you highlighted. Hopefully this will be more apparent in the second photo below. I also began adding some "puddles" of oil or other waste that could be building up onto the asphalt and concrete. It is important to not completely cover the "concrete" level of the base as you still want some of the brighter primer color to be visible to identify the level as a brighter material.
Once this first layer has dried, re-apply the Agrax Earthshade in the same manner to deepen the shading. I prefer to shade smaller areas in regards to the "puddles" on the ground as it adds some more texture and shades of color in them. I also added some Seraphim Sepia to the borders of some of the puddles on the ground levels to further add more color interest.
The final steps are to thin down Reaper Master Series Rust Brown to a wash/glaze consistency. I then apply this as a glaze to certain shadow areas across the rubble and bricks. This is applied very sparingly and is just used to add another accent color and touch of detail as it is much more opaque and bright in contrast to the other shades used on the weathering of the base. The final touch is to paint the edge of the gaming base with your choice of color to cover up any spills or misplaced paint that may have gotten on it. Voila! You now have a pretty cool city-scape base for your miniature!