Imitating the look of straight pieces of metal tubing may be done fairly easily using the gradient capability of PSP 7, but curved tubing is slightly more difficult. Luckily, we can use the very convenient properties of Vectors to help with the job.

Start by opening a new file of convenient size, and having a black background (File > New.) The ones shown here are 250 x 250 pixels. Set your Foreground color to white, and your Background to Null. Using either the Preset Shapes tool or the Line tool, draw a curved shape. Set your Line Width to about 30, and make sure Antialias and Vector are checked. Any other boxes on the Tool Options Palette should be left UNchecked.
 
 

After you draw your shape(s), duplicate the vector layer twice (Layers > Duplicate). When you're done, your Layers Palette should look similar to the one shown below.
 
 

Make sure that your vector objects are selected (as indicated by the square guide box.) If for some reason your vector object is not selected, you'll need to select it by either clicking on the shape in the Layer Palette, or by choosing the vector Selection tool and drawing a box around your object.  Next, create a Selection (Selections > From Vector Object..) A marquee (marching ants) should appear at the edges of the vector object.  This selection should be left active for the rest of the tutorial.
 
 

Now go to your Layer Palette and turn off the visibility of the top two layers. This is done by clicking on the little eyeglass icons, which should cause a red X to appear over them. Next, choose the first vector layer, the one right above the Background. We're going to convert this layer to a raster layer (Layers > Convert to Raster) so that we can do the next step. When you're done, your Layer Palette should look like this:
 
 

Now apply a Gaussian Blur to your shapes (Effects > Blur > Gaussian Blur.) Use a radius of 10 for the effect.  This should cause the edges of the shape to darken.
 
 

The edges are now dark, but not quite dark enough. To darken them further, go to Colors > Adjust > Hue / Saturation / Lightness. Set the Hue and Saturation to 0, and the Lightness to -45.
 
 

Now we put those other vector layers to use. Go to your Layer Palette and click on the next layer up (the one labelled "Copy of  Layer 1") The white shape you originally created should reappear. Next, click on the little "+" symbol in front of the layer in the Layer Palette and then double click on the name of your shape in the list. This should pull up the Vector Properties dialogue for your shape. Change the Line width from 30 to 5. When you're done, convert the layer to Raster (Layers > Convert to Raster.)
 
 

At this point we apply another Gaussian Blur (Effects > Blur > Gaussian Blur.) This time, however, use a Radius of 4. The tubing should now have a clearly 3-dimensional look to it, but it still needs a bright highlight to look metallic.
 
 

To create the final highlight, choose your top layer within the Layer Palette. Again, click the plus sign and select your shape. This time, when you adjust the Vector Properties, change the Line Width to 2 pixels.
 
 

Finally, convert the layer to Raster (Layers > Convert to Raster) and apply a Gaussian Blur (Effects > Blur > Gaussian Blur) with a Radius of 1.3.

To isoalte your tubing for use in a project, simply copy shape (Use the Edit > Copy Merged command), and paste as a new image (Edit > Paste > As new Image.)
 
 

The resulting tubing may be colorized and adjusted in any number of ways. One comment though: the tubing made from bezier curves looks best if you slice off the ends, so it's a good idea to start off with a curve that is a bit longer than the one you want.