There are two approaches we recommend to scaling characters with Limber - one for 2D, and one for 3D. In 95% of cases we expect people to use Limber in 2D, but there are some cases where you might need limb layers and controllers to work in 3D space.
Limb layers have expressions on them to prevent them from being transformed, because it would alter the internal, co-ordinate space of the layer and mess everything up. So you can't simply alter the Scale of a limb layer to make it bigger. But if you want to scale a character as a whole, you can do so using the Size Scale property and a ‘master layer’ for you character.
A master layer would be a layer that every layer in your rig is ultimately parented to in one way or another. This layer’s Scale transform property should match the Limber effect’s Size Scale property when your character is at it's 'normal' size (the simplest thing is to have them both at 100%). Make a new expression on the Size Scale property, and pickwhip it's value to the X or the Y Scale value of your master layer. Make sure Link Length to Size Scale is checked on. You can then alter the scale of the master layer, and the limbs will scale up with the rest of your character.
If you’re using FK Controllers in your character, then you’ll probably need them to scale with the Size Scale property, so that the hands or feet layers that are parented to them also scale. You can do that by pickwhipping the FK Controller’s Scale property to the master layer’s Scale property, in the same manner as above.
A default bone’s Stroke Width property won’t scale up automatically like tapers do. If you need bones to scale, check out the Limber 101 video on the aescripts YouTube channel, or consider using a customized bone from the limb library - some of which do scale automatically with the Size Scale property.
You can use Limber natively in 3D space without pre-composing, but it is not something we recommend for less experienced users. There are some best practices and gotcha’s to look out for.
The recommended method is to use a ‘master controller’ as mentioned above. Make sure all of the layers in your rig are ultimately parented to the master controller. But, for use in 3D you should also parent the limb layer to the master controller. Enable the 3D switch for every layer in your character, including the limb layer(s), controllers and master controller. If you want to move your character in the Z plane, alter the Z Position value of the master controller only (we recommend separating dimensions on the master layer to make this easier). If everything is parented correctly, the entire character will move in Z space and still function normally.
If you add a new FK or Joint Controller to a 3D limb set, the new layer will be 2D, and it will need to have it’s 3D switch enabled. Because these types of controllers have their Position controlled by expressions, the best option here is to parent them to their relative limb layer. Once you’ve done both those things, they should snap into the correct position in space.