He looks like a middle-aged creep who bulked up in prison and then put on fifteen pounds around his middle... except for his MATD. His manifestation looks like a steel coating on parts of his body, and he's done this for long enough that there are steel patches permanently set on his skin now, including a nasty one on one cheek and some on his neck. The rest of the patches are under his clothes. When he does the 'steel blades on each arm' bit, he sometimes ends up with a little bit more steel manifested on his skin. If he wasn't such a psycho, you would think he would stop doing it.
He's an ordinary 6 feet even, of average build, and a few pounds overweight for that build. And you know the scene in T2 where they call home and the T-1000 is pretending to be John's foster mom? Looking quite normal except for the arm that turns into a big swordblade right through the foster dad's head? Tinsnip's armblades look very much like that. Only, Tinsnip himself looks far more like the foster dad than the foster mom. Tinsnip can do some of the same metal manifesting tricks that Silver can, only Tinsnip manifests something that is basically an iron alloy.