What do you use to drill and attach those bones? Would it work for smaller ones?
It does work for smaller ones! Look up "[animal] articulation tutorial" for step by step process.
What I have going for this deer is multiple sizes of wire, from 9 gauge to 24 gauge weights, and a piece of rebar for the spine.
I use hot glue to stick non-weight-bearing parts and to be a placeholder for where I will drill and wire things in the future. Hot glue sets instantly, is easy to pull apart and is easy to remove with rubbing alcohol. This makes it good for temporary fabrication but not so good long term.
For long term, you will want to drill holes in the bones and glue wires between them. This is much stronger than glue and adds a small degree of posability. It's SMALL though, so pick your final pose before you start drilling. Skeletons to not have hinges, but rather slide and rotate within sockets, which is impossible to do without the cartilage, flesh, muscles etc.
Posable, manipulatable skeletons will have much more visible wires and springs and are a whole other beast than simple articulation
This joint isn't going much of anywhere but that's ok because I drilled the holes to connect it right where I wanted it to stay in the final pose.
For big joints and the spine, I used a steel-epoxy mix since those have to bear a lot of weight.
Smaller animals can use tiny holes, thin wire, and glue. If you're careful to take the tail out before all the connective tissues dissolve, you can pose it naturally by soaking in water, posing, and drying in position.
In Very small animals, the connective tissue throughout the skeleton is thin enough to dry out without rotting. Meat will turn brown and cartilage will turn yellow, so it's not the cleanest look, but I like it. There's a bit of gluing to do but if you're careful in the cleaning process, the only wire you'll need is one to pose the spine. Pose when wet, let dry, and glue the remaining bits together.
This deer is my first full articulation as sticking rodents in orbs takes considerably less drilling.
Remember to decide on your pose before you start drilling!