I am new PTC Creo, I have used SDRC I-DEAS and Siemens PLM NX. I am trying to create a non-circular tube that will have an ellipse along the bottom portion of the circular sketch. I would like to know if it is possible to select individual curves to create the extruded feature that I want to create? I have attached a screen shot of my sketch.
if you want to use portion of existing curves, then go to Sketcher mode and use Project command to copy existing geometry.
I don't really understand your request but if you want the sketch to include geometry but not use it, convert that geometry to construction using right click or ctrl-g when it is selected.
Maybe you are trying to build something like the cap on the end of a tank? "Non-circular tube" and ellipse.
I think you'll have to clarify your question to get better answers.