Thanks!
Here are some attempts at Middle Earth orcs. I've been digging out and otherwise amassing orcs that broadly fit Tolkien's conception. The main thing is that they have to be small. I've harped on about it often enough here, but it's very clear from LotR that even the biggest of Tolkien's goblins - the Uruk-hai - are significantly smaller than Men. There's ample evidence for this, but the most obvious thing is that the half-orcs - who are described as "Men" have Orcish features but Mannish height: it's their size that strikes people as odd, because Men - as Gollum observes - are "much bigger" than Orcs. And of course, the smallest ones must be roughly Hobbit-sized (because Sam and Frodo can pass themselves off as Orcs).
Anyway, I'm combining Asgard, Ral Partha, Denizen, Reider and Chronicle in this, so variety is very much a feature. Here are a couple of Chronicle "black orcs" that could work as smallish Uruks or bigger examples of the smaller breeds; I get the impression that there was a blurry line between them - as with the "larger and bolder" of the Northerners who stay with the Isengarders when the rest flee (of course, those larger, bolder Northerners may well be Uruks, as Moria had plenty of them). The Ral Partha "giant goblin" archer is definitely an Uruk, and the Viking is just there for scale.