You can take a flat rectangle, and insert your Bends on this. Then go to your Process-Bends and edit your Flat-Sketch feature.
You will have to add 4 sketch lines to get the flat part to bend into a tube. The 3 dimensions between your sketch lines will be equal, and the distance between the Edge of your part and your first sketch line will be half the first distance. Basically, you are dividing your flat pattern into quadrants, with full quadrants in the middle, and the last quadrant divided equally at both ends of your flat part.
If you need Cut-Extrude features in the wall of your tube, simply Rollback your Process-Bends, and add those features. Make sure you uncheck the "Normal To" option of your Cut-Extrude. When you unsupress your Process-Bends, everything should look good.
Ray Reynolds
Senior Designer
Read: faq731-376
"Probable impossibilities are to be preferred to improbable possibilities."