Stick Nodes plugins.

Give each plugin access to a whitelisted set of objects to manipulate, such as a stickfigure object array or a frame array, give each plugin access to a whitelisted set of functions to call, such as an addFigure() function or addFrame() function, allow for basic scripting language functionality, such as allowing for variables, functions, conditionals, and loops, add some safety restrictions, such as rate limits, and then just whitelist more objects and functions as you feel comfortable.

Maybe give each plugin a sub-menu in some kind of parent plugins menu, where parameters of the plugin can be edited or functions of the plugin can be called.