These are some live examples of what you can do with tortuga.
variables : X, F constants : +-[] axiom : X rules : (X → F-[[X]+X]+F[+FX]-X) (F → FF) angle : 22.5°
variables : A, B constants : +- axiom : A rules : (A → A+B++B-A--AA-B+) (B → -A+BB++B+A--A-B) angle : 60°
variables : F constants : +- axiom : F++F++F rules : (F → F-F++F-F) angle : 60°
variables : F constants : +- axiom : F-F-F-F rules : (F → F-F+F+FF-F-F+F) angle : 90°