I was wondering if anyone could give me guidance on the construction of a cryocooler in a DIY setting. As a tinkerer, builder, and a chemistry major with an interest and dabbling in mechanical / system engineering, I want to try my hand at building a cryocooler for liquefaction of small amounts of nitrogen for experimental purposes. Justifiable uses of such include chilling beer (ha!) and use with friends in supercooling setups on overclocked processors. Now, the only information I could find online were all reiterations of the same setup! Which necessitate the use of a Stirling free-piston to make the magic happen. For a project like this the availability is near nil, and especially on a DIYer's budget. I have a great deal of common sense and aptitude when it comes to designing such things and using the knowledge I've been lucky enough to receive, so I know that except for special circumstances there is usually more than one way to accomplish a task or process. My first-line questions revolve around a) is there an alternate way in the realm of feasibility to accomplish this, and b) if not, is there a way to manufacture a Stirling piston that has an acceptable level of efficiency? I have a great deal of separate, disorganized ideas on the issue but I'll spare you all the thinking out loud until those thoughts become relevant.