This model has solid and hollow versions. However, the hollow version is not to make the walls super thin and minimize weight/resin, but rather to balance the model to stand more firmly. An actual chicken's center of gravity is further forward than a solid lump of resin in the same shape, since most of a real chicken's rear volume is fluffy feathers rather than dense body.

If you are printing a very small chicken, say 25.4mm/1in or smaller, just use the solid one and base it. There is very little balance difference between the solid and hollow versions at a small scale. Small models can still stand on their own but will be very prone to tipping, so it's better to base them. I included a small presupported base like the one in the photo of the painted model. However, if you're making a big chicken model, use the hollow one and you likely won't need a base unless it's going to be on quite uneven surfaces. My larger, 2in version shown in the photos was printed from the hollowed version and it stands quite robustly on its own. 

I included supported versions for 1in models. For bigger models, the supports don't scale well but are pretty easy to auto-add with Chitubox, so they are best done on a case by case basis. For bigger than 1in, just auto-add some medium supports, consider adding some thicker/heavy supports on the rear, and then check the feet and edges of the wattles to see if they need some extra light supports. The weight/area expands quickly if you print from the same angle as the 1in presupported examples, so err on the side of heavier supports than you think you'll need on the back of the model. 

Some easy painting ideas to get a couple of realistic chicken colors: a yellow base with a couple layers of sepia wash will make a brown chicken with highlights like the pained example. A white base with a sepia wash will make a lighter yellow/golden color still with a hint of brown (it will look like "buff" in chicken color terms).