Strategies for tool designs and their uses wherein the tools can operate in either closed or open modes of operation. The tools easily transition between open and closed modes on demand. According to one general strategy, environmentally controlled pathway(s) couple the ambient to one or more process chambers. Air amplification capabilities upstream from the process chamber(s) allow substantial flows of air to be introduced into the process chamber(s) on demand. Alternatively, the fluid pathways are easily closed, such as by simple valve actuation, to block egress to the ambient through these pathways. Alternative flows of nonambient fluids can then be introduced into the process chamber(s) via pathways that are at least partially in common with the pathways used for ambient air introduction. In other strategies, gap(s) between moveable components are sealed at least with flowing gas curtains rather than by relying only upon direct physical contact for sealing.