How to Mask off a Model for Airbrushing

Say you've seen an awesome video about how to airbrush power weapons.  You want to do the same but the model is already assembled.  You don't want to airbrush paint over your model or its fancy base.  Tried three different ways to mask off my Purifiers while airbrushing the halberds.

Much like roshambo except blue tape, saran wrap, zip lock bag.