Apoxie Sculpt - A durable 2 part clay. Typically used in gap filling and the creation of odd geometry. Incredibly hard and strong, but brittle.
Expanded PVC Foam (Sintra, Komatex etc) - A foamed plastic which is my workhorse for props and armor. Tag line for the product is "It's like wood, but better." While much more tough and ductile than wood it lacks the hardness and stiffness aspect of wood. Can be heat shaped, but use caution due to resulting fumes.
Acrylic Extrusion - Shaped plastic bars that come in several shapes. Useful for trim work that requires high precision.
Bondo Auto Body Filler - Hard filler similar to Apoxie Sculpt, but cure time is matter of minutes rather than hours. Useful for quick gap filling, but not as precise in application process.
Loctite Professional Liquid Super Glue - Go to glue for plastic to plastic applications. Low cure time, high failure strength.
E6000 - Go to glue for plastic to cloth applications.
Loctite Power Grab - Go to glue for plastic to wood applications. Super glue performs best if wood is sanded smooth.