Sexing :

Skinks as a rule are considered hard to sex, and Cunninghams are probably more difficult than most. Bartlett (A-Z of Lizard Care) says that they were convinced one specimen they had was male until she produced a litter of young one summer. No hemipenile bulges are visible, but probing (done by an expert!) may prove if an individual is definitely male.

Housing :

It's not too difficult to house Cunninghams, provided you can provide the space for them. Being 12-18" in adult length, they require roomy terraria, and I settled for one 4' x 2' x 3'. Height, however, is not important as these skinks are strictly terrestrial and in fact somewhat saxicolous (dwelling among rocks). Rocks are indeed important for the well-being of Cunninghams, and most writers recommend a jumble of sturdy rocks in the cage for both basking and hiding. This raises one important point, namely to make sure that your vivarium or tank can bear the weight of so much stone. I would certainly not recommend using an aquarium to house these lizards for that reason, and even if you are using a wooden vivarium you should make sure that the bottom is not going to drop out. I still have the occasional qualm about keeping ours on top of the monitor vivarium, even though the latter is 6' x 3' and very sturdily constructed. Another thing to beware of with all rock-dwelling creatures is that their eagerness to tunnel in between rocks can lead to the rocks collapsing on them (with fatal consequences) unless the rocks are secured. If you wish to make a rock hide for your captives, it is often best to glue the rocks to one another to lessen this risk. Aquarium sealant (silicon-based) is recommended. I have used large pieces of bark in addition to the rocks provided, and the lizards seem happy to use these as hides. One of them also persistently squeezes under the heat mat when it is not switched on.

By the way, an amusing but instructive anecdote: if you are loading a vivarium sideways into a vehicle, make sure you take the glass doors out of the vivarium first! I didn't, and as we tipped it over on its back they both fell inside and smashed to pieces. Take heed! 

Feeding :

Like a lot of medium-to-large lizards, Cunninghams Skinks are fairly easy to feed but do need a variety of food. If you keep Blue-Tongue Skinks you can feed Cunninghams a similar diet but with a greater proportion of insects and less veggies. My own feeding routine for my pair was on the same rota as the plated lizards, but with a few slight differences. Both groups of lizards (Cunnighams and Plateds) had a routine where they got fed 2-3 times a week, usually every other day with a two-day gap between meals once a week. For the Cunninghams one feed would normally consist of black crickets (not too many of these as the chitin can be hard to digest), one of vegetables and fruit, chopped and placed in a bowl, and one of king mealworms (Zoophobas) or occasionally of two pinkie mice each, dipped in calcium powder (eg Nutrobal), since they did not seem overly keen on these but would eventually consume them. In any event, insectivorous or omnivorous lizards should not be given too much animal protein. The best ingredients for the veggie dinner are paw-paw fruit (also known as papaya), water cress or mustard and cress, and one of the following: mixed vegetables (peas and carrots, normally thawed from a bag in the freezer), a chopped up strawberry, a couple of leaves of kale or spinach, and a few slices of ripe mango or banana. Note that kale, spinach and banana should only be given sparingly, as the first two items contain an oxidant-binding substance and the third is quite fatty for reptiles, although they love it. Hal Cogger notes that in the wild this species consumes much fruit and seeds, as well as arthropods and small vertebrates. A bowl of water should always be available (not too cold). 

Tameness :

If you are used to the tameness of Blue-Tongue Skinks or Plated Lizards, you may be disappointed with Cunninghams. Egernia cunninghami in my experience tend to revert more to the usual skink characteristic of secretiveness and flighty retreat if they are exposed to the sight of a human, at least initially. Like a lot of nervous lizards, if handled they will also try to bite, and believe me they can bite, hard enough to draw blood. For this reason I recommend you purchase a tough pair of smooth gardening gloves if you wish to handle your Cunninghams. Once I was handling the male, Tucker, when he bit hard on my gloved finger. I was able to draw my hand out of the glove without any discomfort and had the amusing sight of Tucker sitting in my grasp still pugnaciously clasping my glove in his jaws until he grew tired of this game. It took months to get to the point where these skinks would not run away to hide as soon as they sensed my presence in the room, but eventually they would normally remain basking or sitting when I came in provided that I did not stare too long at them - eye contact (or lack of) seemed quite important to them.