[lisa]

Actually, the girder is not significantly different than your map. You've got the right idea.

To make the sharper edges on the corner, I used the "divide loop" plugin along the faces that I knew were going to have hard edges. (If you already have enough loops, you can skip this step.) Then, I squashed the surfaces together to sharpen the edge--on the model itself, not the TCE, for clarification. If you have subdivision mode on, you'll see the model will get much sharper even with the subdivisions maxed out.

You can adjust the UV map similarly to the model if you need more resolution, but on the girder I just kept the default map from the sculpty cube and adjusted the model only.