What type of devices, could increase dim sum output, short of a complete expensive, automatic machine?
Three sets of tools would help you speed up your operation, with some caveats:


Circle cutters, particularly ones that allow you to cut a lot of circles together like this kind.
Dumpling molds in a variety of sizes.  There are even some that mold-and-cut, but that's not actually a big help since you have to "pre-cut" the dough anyway.
Cookie scoops for portioning fillings.


The biggest speed-up here comes from having sets that match: cutters that match the size of specific dumpling molds and a cookie scoop that portions exactly the amount of filling for those molds.  You'll also want at least a half-dozen molds of each size so that you can assembly-line it.

Now, the caveats: first, molded dumplings will never look as good as hand-folded.  Second, certain shapes aren't possible using a plastic mold, such as Siu Mai or the classic Har Gow shapes.