Tailored functionality, compactness, and reliability continue to be needed in optical communication devices. Our processes for prototyping and validating low-loss planar polymer waveguide devices can respond rapidly to these needs through the steps described herein. In the past two years we have prototyped several distinct thermo-optic devices and established process- and product-reliability that is broadly applicable. Our prototyping and validation processes consist of modeling, waveguide fabrication for verification of design rules, optical characterization, heater fabrication (for thermo-optic devices), and bare-chip accelerated aging. First, modeling provides insight into optimized designs that can be fabricated with low-loss polymers. These designs are subsequently verified by experiment. Optical building blocks, such as bends, splits, and crossovers, have been characterized, and selected for use in the design of devices for applications such as switching, variable attenuation, and wavelength selection. Resistance heater dimensions and waveguide structures are optimized for maximum thermo-optic effect, minimum response time, and operational stability. As an example, a 2x2 thermo-optic switch, characterized at 1550 nm, has a maximum insertion loss of 1.8 dB, polarization dependent loss less than 0.1 dB, and switching time of less than 3ms. A robust waveguide fabrication process combined with a rapid prototyping ability provides the ability to efficiently evaluate design options. Short term and long term statistical data show that the fabrication process is in good control. Environmental screening tests combined with high temperature aging under various conditions of atmosphere and electrical power provide an efficient means to evaluate materials and processes, estimate product lifetime, and isolate failure mechanisms.