A free throw away pallet should have all the wood you need. You'll just be out the hardware and the labor.
You can make a sawtooth pattern on a board. A ratcheting prop moves across the sawtooth and holds the headgate at whatever position you put it in. The animal can't open it as the ratcheting prop holds it from opening until you release it. A bungee cord will engage the prop firmly into the sawtooth cuts in the board. This will allow the gate to accommodate different size animals without making a traditional "tools needed" adjustment.
If you make a non-adjusting gate yo can make "spacers" that attach to the curved neck hugging part to accommodate different sized animals.
The combination squeeze chute/head gate I use would let the smallest of my heifers pull their heads out (under 400 lbs or so depending on the individual) even when fully closed. They are growing so fast that is no longer a problem but next batch of little ones will see a space to shrink the gap.
Pat [img]/forums/images/icons/smile.gif[/img] [img]/forums/images/icons/smile.gif[/img]