As requested, this is my attempt at showing how i created my recent entry called 'Feathered'
I'll show step by step a series of images to help you understand how it was done.
You will need Photoshop CS4 or CS5 to be able to have a go at this yourself.
Step 01.
First you will need to seperate the seeded area from the background, there are many methods to do this, and i guess you need to follow which ever method you like.
Step 02.
Next you will need to remove the seeded area from the background, you can again use various methods, i used a mixture of 'Cloning' and the 'Patch' tool.
Step 03.
This next step is a preperation for a mask that will be used a little later.
I made this by making a plain black layer below the seed layer and then turning the seed white, this must then be saved as a jpg.
After saving it i then used undo to put the seed back to normal.
Step 04.
Ok the next step is to select the seed layer and turn it into a 3D object, i used the Donut shape for this.
Step 05.
This next step is where you will need to use the black and white mask made earlier.
On the 3D objects layer, you will see that the thumbnail has a small box in the lower right corner, click on this to bring up the 3D properties box.
Across the top are 4 icons, the 3rd icon is '3D Materials', next to the 'Opacity' setting is a drop down box.
Here you will need to click on 'load texture' and choose the mask you made click ok.
What you will see, is the grey area of the 3D Donut disappear leaving just the seed wrapped around the Donut shape. You can then use the 3D move tools and see what it looks like from other angles.
Step 06.
Hide the 3D layer for the time being.
Duplicate the background layer and turn in into a 3D postcard.
This layer will become the base that the object will sit on.
Step 07.
Turn the seed layer back on and select both 3D layer at the same time.
Next go to the 3D menu at the top and select 'Merge 3D layers'
The seed image will disappear, this is because Photoshop will position the 2 objects how it feels it wants to.
You will need to use the 3D move tools to reposition each object to a position you like.
The move tools can be complicated to use, its a good idea to play with each tool to see what it does.
Step 08.
You will notice that the seed 3D object is now black in colour, this is because there is no light shining on the object and so it is in darkness.
This next step is where we will turn the lights on, select the 4th icon in the seed objects 3D menu (it looks like a light bulb) on the bottom of this menu is where you can choose to add new lights to the scene.
I chose a 'spot light' for this image.
You will need to use the move tool for the lights to position it how you want to, you will see the seed object light up, but no shadows will appear until the object is rendered.
Step 09.
Ok almost done.
Here is where we get to see how the final image will look.
Click on the first icon in the 3D menu and select 'scene' here you can select the quality level.
Choose the 'draft' setting, Photoshop will begin to render the image, making shadows on the object and on the base.
If your not happy with the light position you can change it before the render process has finished, just click on the light setting and rendering will stop, just move the lights to how you want and try again until you get the effect how you like it.
You can choose a better quality setting, but this will take longer to render.
Well this is the final image.
I hope this has given some insite into Photoshops 3D abilities and most of all that you have managed to understand this tutorial as its my first.