Patterns for what? Gear? Clothing? The pattern design software I've used (none of it heavily) is basically 2D CAD with features specialized for garment pattern making, and quite expensive. If you're doing gear, and working on a personal scale, Drawing in a 2D cad may be the easiest solution. The sewing specific features either won't matter, like grading (process of changing the pattern for different sizes) or marker making (figuring out how to lay out the pattern pieces so you use the fabric most efficently. Very hard problem.) or can emulated -- seam allowances are just offsets, for instance.
There are also (expensive, of course) plugins for 3D systems to make 2D drawings (and cut instructions, etc).