Can gas pressure and density be reduced without changing temperature?

[mishima]

I'm curious from a lab sort of perspective, how does one keep a gas at a constant temperature yet decrease both pressure and density? Like how could I reduce the pressure of argon gas with the gas kept at room temperature? Put it in a vacuum larger than the space it normally occupies or something? How is that constructed?

 

[maimonides]

Yes, you have to change the volume (or the amount of argon). Then you may have to wait for thermal equilibrium.
What about a cylinder with a moving piston?