<p>I was wondering if anyone could give me tips for designing a 3d printable structure that can "pinch" down onto a hockey puck shaped piece and hold it tightly. </p>

<p>I'd like for the structure to normally want to "pinch" two edges together, but I can pry/force them open when I shove the hockey puck into it. Once I let go, the two ends are now holding the puck fairly tightly.</p>

<p>My first thought was something like a potato chip bag clip, but that would require a couple pieces and a spring.</p>

<p>Is there a way to do something like this with one solid piece?</p>

Here are first 3 the most simplified and generalized options you have:
All you need now is to give use more details about your needs. If you reveal more details we could help you to apply (and modify) one of these  options.
Each of above has its own pros and cons of course. You said you don't want to have spring... so maybe a rubber ;)
But in fact whole-red is one-piece-clip in which the force comes from material elesticity or stiffness.
Please tell me what is the application of such clip.