The Chaos Dwarfs are the most noted discontinued army in Warhammer Fantasy history. I imagine most of the old "big hat" sculpts probably came from one sculptor who either decided he didn't want to do them anymore, or (more likely) he is no longer with Games Workshop. Certain Chaos Dwarf teasers come out now and then... like the Hell Cannon with the current Chaos Mortals army. These models look more like the old 2nd Edition Chaos Dwarfs (bad looking dudes without the cheeky big hat).
Never the less, the Big Hats developed an affectionate following in Warhammer circles and remain revered primarily due to their nostalgic past. While I was collecting a Big Hat army, my buddy Tim Murray was playing his army. During a moment of weakness when he needed money, I bought his army from him and sold off my own collection on EBay. The one problem I had with the Big Hats is that the army looked like it needed to be uniform in appearance. In other words, if they were going to wear silly big hats, they should all look uniform like the British army of old. Due to my lack of focus on my own models, mine did not have nearly the consistency or cool look that Tim's collection had.
Since acquiring Tim's collection, I have occassionally added my own models to the collection (copying his paint scheme).
Collection Stats:
266 models
243 painted (88%)
Largest legal force I could deploy with painted models: 4,500 points
Estimated Goal Force Strength: 5,000 points
Characters

The Chaos Lord on the Great Taurus. Model painted by Tim Murray.

Sorcerer Lord on a Lammasu. I had trouble envisioning what this model would look like as Games Workshop's studio model was ridiculously silly. But, by dumbing down the red mane to make it consistent with the beards and hair of the Dwarf Warriors, Tim did a great job of making this model look believable.

These models represent the Chaos Dwarf General (a Lord character) and a Hero; each deployed with rank-in-file units on the table. Both of these models are by Tim Murray. Most of my army still needs shields to be added to them (Tim's models were lacking substantially in this regard). I have a pack of Chaos Dwarf decals that will probably go on the shields prior to applying them to the models. The addition of the shields will be significant since I often field the warriors with a heavy weapon & shield combination; confering a 3+ armor save in close combat.

2 of the most significant models in my collection are these rare Sorcerers I picked up from Reaper before Reaper had established itself as a viable figure company. I think I ordered them from the owner over the phone while he was working his old day job! I had fun with these models, giving the one on the left a pair of Converse All-Star shoes while the purple Sorcerer has ruby slippers. To Tim's chagrine, the sorcerers he sold me with his collection lost out to these two and were spun off on EBay.
The necessity for a 3rd Sorcerer came up when Tim modified the balanced list for the Collector's Tournament (under the correct claim that the 10 Hobgoblin Wolf Riders were too much of a liability). This is a Reaper miniature that I chose to paint up for "the dark side." He has a large skull pendant on his back, which led to the decision.
Core Units

The backbone of the Chaos Dwarf army is the warriors. Typically I field them in 3 units of 20 with great weapons, heavy armor and shields. If I were to expand the army in the future, I'd add units with hand weapon & shield to take advantage of the 3+ armor save. Unfortunately, all of the vintage Chaos Dwarf models have great weapons.
Here are some close-ups of the command groups showing some of the detail and the themed banners that Tim made for the army. The banners are all images from the Internet. He chose to stick with a volcano or mushroom cloud theme.
As Banners go, this large banner is often used as the Battle Standard Banner for the army.
I consider the Blunderbus to be the "must have" unit of the army, either deploying them in 2 units of 15 or 1 unit of 30. I've been considering increasing the units to 2x 20, but this requires searching EBay for additional models (which are hard to find) and I'm not sure if I intend on adding anything more to the army at this point.

Like the pair of Sorcerers in the Army Roster, these models are all from Reaper Miniatures before Reaper had formed into the miniatures manufacturer that it is today. These are lead models that were sold for 99 cents each at the time. Since these are from my original collection, their paint scheme is not consistent with the rest of the army that came from Tim Murray. At some point, I will have to force myself to bring them in line with the rest of the collection, but at the moment, I like to keep them as they were originally painted some 15 years ago.

Tim didn't have any hobgoblins in his army, therefore, all of the hobgoblins (on foot, anyway) are from my original collection. Although these models show signs of washing on their skin tone, the glossy overcoat indicates that these models were originally painted over 10 years ago. I have recently added more models to the unit (doubling it in size), but used the same method as for the old models so that they blended in a little better. Shield decals are from Chaos Dwarf and Chaos decal sheets purchased from GW back in the days of 4th Edition.

This shot reminds me of the "Spirit of 76" painting with the fife and drum. This is the command group of my "red" hobgoblins. The banner is a color scan taken from the 4th Edition Chaos Dwarf army book.

The original models for my "blue" unit of hobgoblins were purchased on EBay. It, too, has doubled in size due to recent additions, which include the command group. These models were done with Foundry paints.

Like the "red" hobgoblins, the banner for this unit is also scanned from the 4th Edition Chaos Dwarf book.

These Hobogblin Archers were painted much later than my other Hobgoblins as evidenced by the quality of the paint work and the lack of any shiny glaze on them. I still haven't ruled out their tactical importance in the army (which explains the completion of so many of them late in the history of the collection). Perhaps, combined with the Earth Shaker, I could make a viable shooty army? I am also working on incorporating them into the Mourngols amy list for an Eastern Hobgoblin Army. The Eastern nomads tended to hide within their wagon laager and defend them with bows, but I haven't found a gaming equivelent yet with which to validate them.

This close-up shows 2 archers and a horn blower recently added to the collection above. Although their armor is red and the caps are a variety of bright colors, painting the tunics in Bubonic Brown helped to keep the entire group looking less toy-like than the red hobgoblin unit above.

Speaking of the Mourngols, this is a unit of Hobgoblin Wolf Riders from the collection I purchased from Tim Murray. They are still based consistent with the Chaos Dwarfs, but will eventually be rebased for use in a full Wolf Rider army. I believe in fielding at least one Fast Cavalry unit per army, but a glitch in the conversion from 4th Edition to now still requires 10 models to be fielded (rather than 5 as a minimum, which is what all other Fast Cavalry units require). Anything above 6 models is wasted in a Fast Cavalry unit, which makes this unit unattractive at the present time. Too often I have extra Wolf Riders fleeing off the table. Once I get some of my armored, spear armed Wolf Riders painted, I may attempt using them as a shock unit, rather than a harassing Fast Cavalry unit.

Close-up of 2 Wolf Riders with bows.

This unit of 3 Wolf Riders is a test I painted back when I was working on the Hobgoblin Archer unit. I chose to use the similar color scheme on the Wolf Riders, which should affect the appearance of a large Mourngol horde. Seeing how Tim started me off with a large unit of black clad riders, I had to mull over whether or not to continue with that scheme or change it up. These models indicate the direction the Mourngol riders will be taking.
Special Units

These Bolt Throwers are old RAFM models that came with a Lizardman Legionaires army released about 15 years ago. Rather than fussing with how to incorporate them into my regular Lizardman army, I chose to crew them with Hobgoblins I purchased separately from Games Workshop.
These two Death Rockets are from the original Tim Murray collection. They're some of my favorite models, probably because of the details Tim put on them to contrast with the dark brown and black over-all color.

The paint scheme on these Sneaky Gits was taken from the Black Guard of an Arab Shiek. However, at the time I didn't realize that Shadow Grey had a purple tint to it. As unhappy I am with the paint scheme so many years later, stripping them and repainting them is not on my list of considerations at the moment.
Rare Units

The Bull Centaurs occupy an awkward position on the army roster, being a Rare Unit choice but ineffective enough to justify their rare existence. Therefore, I tend to field them in a variety of options (2 smaller units, one small and one large, one unit or none at all as I choose to field Earth Shakers instead). Tim painted all these models.

Close up of the Command group.

This Earth Shaker model, the better of the two, is the one I use most often (due to the projectile coming out of the barrel).

This less elaborate model seldom sees action as it would take up another Rare Unit slot (competing with the Bull Centaurs). Never the less, I can envision a day where it may be viable to play a pair of Earth Shakers in a siege or shooty army.

To keep track of wounds on multi-wound models, I currently use Wound Markers from Gale Force 9. However, as each army nears completion I like to paint up casualties that get placed next to the model that is wounded. These are Mordheim Dwarf casualties that I painted up for the Chaos Dwarf army. Although they don't have Big Hats, I didn't feel like putting that much effort into what amounted to a casualty marker.