We describe a domain-specific design tool capable of creating and fabricating complicated curvilinear patterns within the early stages of the design.  This tool entitled “[SIN]uousi is a parametric design application that allows both the customization and fabrication of dynamic patterns created by the combination of SINE and COSINE functions.  This tool allows designers and architects to design curvilinear patterns and manufacture schematic physical models of them in a short period of time, using rapid prototyping equipment such as a laser cutter.  This tool consists of several modules, including a pattern maker, a fabricator, and a 3-D simulator.  Using this tool, patterns are generated by manipulating variable parameters and fabricated according to the assembly sequence easily and quickly through algorithms by locating nodes of intersections.  The end result is an exported computer file compatible with laser cutting technology.  We expect that this design tool will facilitate the transition between the virtual and the physical, thus resulting in a better design product.