We introduce the 3D warp brush, a method for interactive shape modeling in a immersive virtual reality environment. 3D warp brushes are implicitly-definedtools that operate on triangle meshes. We combine the efficiency of explicit mesh representations with implicit modeling operators. The area of influenceof a 3Dwarp brush can be of arbitrary shape since it has an associated distance field. We define different warp functions including drag, explode, and whittle. A unique feature of our framework is the ability to convert meshes into 3D warp brushes at run time. The use of a Responsive Workbench and two-handed interaction allows the user to exploit the full potential of the modeling system by intuitiveand easy modification of a base surface into a desired shape. We present models, which have been created and modified using 3D warp brushes, to demonstrate the usefulness of our framework.