its a good idea but its better to find a metal tip that has a really small hole as opposed to your unique screen idea, the metal in twist ties is very malleable(bendy) and most malleable metals have a low burning point, and even if its not burning my bet is its giving off nasty toxins.

An even better thing to do would be to go and pick up a glass one hitter from a shop cause then all your smoking is weed and it tastes 50 times better, plus its been proven that even though the lighter flame is not directly on the plastic the smoke is still hot enough to activate narsty chems in the plastic which we all no is a bad thing

but a pen pipe was my first smoking device i ever made and i know that they do get the job done pretty well