I found some really helpful tutorials online, but thought there was room for one that really took a step by step approach.
Here is what you'll need:
MDF Bases - I got a 2' x 4' piece of 1/4" thick MDF for $7. I used a cheap $8 saw to cut it into a bunch of sections and then used my Dremel to clean the edges. You could easily use a sharp blade to clean the edges instead. For bigger buildings I go with a 12" x 12" piece, for everything else I use 8" x 8".
Bass Wood - I went to AC Moore and got a bag of wood pieces. I had lots of long sticks and pieces of board. That bag cost $6 and was enough to make 10+ buildings.
Wood Glue - Big bottle cost $5 at Home Depot.
Spackle - Small tub of spackle and a plastic stick to apply it was about $4.
Exacto blade - $7 from Hobby Works
Hobby Saw - $8 from Hobby Works
Foamcore - AC Moore had a sale and I got 3 big pieces for $1 each.
Rubble - I cut up GW sprues and then fed them to a food processor to ding them up.
Long Square Wood Sticks - You have to eyeball these, but most craft and hobby stores have long wooden sticks. Find one that is the right thickness so when you cut the foamcore it'll look like proper edging. This saves a ton of time later on!
Measure a 2" strip along each of the edges of the foamcore.
2" is a good height for each floor as it works well with the mechanics of Mordheim and lets you fit most every figure underneath ledges. It also feels right to scale.
Use your Exacto blade to cut these out. I trim along the edges so that you're guaranteed one flat side, which can be important later on.
This will give you several strips to work with later.
Measure out how long you want each wall section to be. I find 4" is a great size for the bottom floor as it allows you to go larger with the upper floors while having everything fit on the base.
Use your Exacto knife to cut into each of the marked areas. Be careful to only cut the top sheet of the foamcore so the back piece keeps everything connected. This will make the rest of the project a lot easier!
Once that's done you can fold the pieces to look like the bottom of the building.
Unfold the pieces and trace out where the windows and doors are going to go. I use a 25mm base bottom for a window and a 40mm base bottom for the doors. Doing this looks "right" and makes for a more playable building, plus by keeping all the pieces measured out it allows me to make framing more quickly.
Once that is done cut the pieces out with the Exacto knife.
Using the base bottoms for guidance mark out where you want to cut the wooden sticks for the window framing. I always make sure to make the top and bottom parts stick out more so that they fit better.
Cut these pieces out and glue them around the edges of the windows. This is one of those details that really helps to make everything look good.
Measure out 2" increments, maybe a little less, on the long square wooden sticks and cut them out.
Make sure to use the hobby saw so you get a more even cut, hobby clippers will bunch up the ends.
Glue each of these 2" sticks to the edges of the building and then glue the bottom of the building to an MDF base.
Notice how the edge posts stick out some, this creates a really cool effect when everything is done.
Cut out another floor section. I chose to go with 6" for this one and included fewer wall sections. Cut out a window and throw some edging on as well.
Cut up a piece of the bass wood to act as a floor for this section. Beat it up a little bit! I like to use bass board overfoam core as it paints up nicer and has texture. Glue this piece onto the edges of the second floor's walls.
Glue this floor on top of the first. Have it hang forward some.
Do another floor! Have this one be a little smaller and cut out a ruined window frame. This is seriously one of my favorite looks in Mordheim.
I spackle the outside facing walls. This gives me them a really nice look when painted up. Adding a little bit of texture really livens up the buildings.
I also use wood glue to glue all of the foam edges. Foam is delicate and gets destroyed by priming the building, which you're going to want to do, and just by regular use. Edging everything with wood glue gives it a strong coat that will protect your buildings and keep the white foam from coming out and ruining the look of your building.
Prime, paint, and base! I prime my buildings black and paint using cheap craft paints. The cheap craft paints are thinner than most hobby paints and this gives the buildings a burnt out look as the primer will show through.
I also got some Mordheim styled posters (they're all over the internet), some Medieval art, and just some other items that I printed up to scale and glued onto the walls. I think this gives the buildings a lot of extra character.
I also flocked the outside areas with regular static grass. I did this so it'd fit in whenever I wanted to use it for games that weren't Mordheim and so I could have a suburb of Mordheim. It's cheating, yes, but it works.
Do this a bunch more times and have a full village of burnt out buildings!
Then go play some Mordheim!
I hope this was helpful! I'll likely be blogging about our Mordheim campaign as it goes along. You can also expect something similar in the Winter as we do Necromunda next!