Pretty much, you might check your local recycling center. I wish they had a us distributor for their hardware. Seems like burning a bunch of jet fuel to get these here kinda offset the benefit.
Their tutorial covers sourcing the parts I think. It all looks pretty easy to bodge from a hardware store as well. You could get the over-center lever from an old bicycle. Not sure how I would do the latching bracket but you could grind/drill something close out of steel flat bar.
Indeed, it can be strapped together with a piece of an old innertube, and the rest can be improvised.