There are a number of rendering programs that work with SketchUp. The image below was created using Twilight Render for SketchUp which has one of the simplest user interfaces and workflows. Twilight Render is a plugin that works within Sketchup under Windows. The full program program costs $99 but the fully-featured free demo version is capable of creating images of up to 800x600 pixels. Although it has a watermark feature at the edges, with a little care when positioning your image, you can easily create images suitable for upload to Quirky (450x320 typically).

memory_latch: 3D rendering (approx 1hr processing)

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memory_latch: Design in Sketchup


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Twighlight is accessed from a toolbar in Sketchup where you can set the lighting conditions and simple properties for the materials in your model. Once that is done you simply move around your model to find the view that you want to capture. Rendering then takes just a couple of clicks but processing times will vary depending on both the complexity of the image and the power of your computer. One of the easiest and satisfying types of renderings to do is 'progressive' where the image becomes less and less grainy. This allows you to stop the process whenever you are happy with the result. Although the example image took around an hour to process, I could have stopped the process much earlier with very acceptable results.

Let me know if you would like more information on the process.
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Here is a brief workflow to get you started...
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A rudimentary example but one that shows a critical point
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First step is to draw a box in SU by drawing a rectangle and then using the push/pull tool to pull the rectangle up to give the box height
Notice as you draw the rectangle that it is coloured a greyish blue but after you pull the box up it is white.
White is the colour of unpainted 'front' faces (or those painted with the default material). Blue is the colour shown on the 'back' faces for the default material.
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The biggest cause of unexpected results in TL?
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The concept of front and back faces is especially important when rendering your model because they are not the same in SU and TL. Let's consider the SU faces method for a moment...
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Every surface in SU has both a front and back face to allow for double-sided colouring in SU
'Front' and 'back' doesn't relate to which face we are looking at, they are just assigned front and back at creation.
Use the orbit tool to look around your model and check that all of the faces are white - this is a good state to be in before you start applying colours.
Reverse any faces that are blue by right clicking them and then selecting 'Reverse Faces'
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As a model is painted, you can confirm how each face is coloured by right clicking the face and selecting 'Entity Info'
- If you see to two white/blue rectangles (split diagonally) then both faces still have the default material
- If the first rectangle has a different material then this is the material that is applied to the front face and definitely the material that TW will display
- If the first rectangle is blue\white and the second has a different material - you might see this in your SU model depending which face you look at but this is the most likely cause for issues in TL.
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The issue is that TL doesn't have front and back faces it just has the one. A hierarchy is used to get between double-sided model to the single-sided materials in TL.
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The material that is rendered in TL is selected based on the following order
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1) Front face material
2) Group or Component material (in SU any face that has the default material will inherit a colour applied to the whole group)
3) Back face material
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You can use this hierarchy for trouble-shooting unexpected results in an existing model, but overall when starting from scratch it is best to keep your model as clean as possible: Avoid colouring the back faces altogether and work only with materials on the individual front faces or if working with groups, leave the individual faces as default and facing outward.
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note: TL leaves any face that isn't painted in one of the above ways as white (on both sides).

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OK so we have a cleanly painted model - how do we render?
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First make sure that the Twighlight tool bar is displayed (View > Toolbars > Twighlight)
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Next, open up the TL interface by clicking on the green power button on the TL toolbar
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You can get a quick and dirty rendering by selecting a preset like 01 Prelim or 02 low and then choose Render > Render from the menubar, or click the first icon (planet Saturn?) to start. Pretty soon you should have your first render.
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You can choose higher order presets to get more impressive results. The main example image above was done using preset 09 Interior progressive render (stop when desired).
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You can return to SU at anytime to change the your view, the materials or shadow settings.
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Changing the properties of the materials
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The default colours from SU show up as dull materials in TL but can be easily changed
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TBA coming shortly! - please go back and redigest for now.
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Tip: if you are moving ahead faster than I am... use the TL colour eye-dropper and then edit based on templates (avoid libraries as there is little control and no major benefits at this stage)

Thanks for this amazing information. Do they have a MAC version of this?

@simplyinclined - Thanks for the info. Did you have the free version when you did yours? I just downloaded the demo and it is a bit confusing. I've been playing around with a simple box for a few minutes, but can't seem to be able to select different parts to have different renderings (ex. one side plastic, one side metal). I'll try again when I have more time, but I appreciate the link.

Andrew, there is no mac version but there is another similar called plugin shaderlight that does do mac. It also has a free version that looks very useful although I've never tried it.

Stacy - I actually stumped up for the full version last month. I should probably give some simple workflow steps (later today).

Thanks for the tip on the plug-in! Very cool. I suck at Sketchup but am playing with it. Would love to see a workflow.

That looks very useful, thank you for posting this.

It looks like you can download it for Mac OS X.

Marc are you looking at Twilight or Shaderlight?

I was just thinking of sketchup. . http://sketchup.google.com/intl/en/download/gsu.html I didn't realize these were secondary features.

Still Learning. Thanks

Ok - no worries. thanks

I have added a basic workflow to the first post. I will post any important additions both in-line and as edits to the first post. Thanks for the interest.

Nice! Thanks!!

My personal favorite, for free 3D apps that are somewhat easy to learn, is Autodesk 123D. It is designed for beginners and it is actually quite user friendly, once you get the hang of it.

Note: It can take a little while to install if it needs to install .NET Framework 4 on your system. One of the great things about the Autodesk system, other than being free, is that you have integrated tools that allow you to send your model off to be created for you (prototype).

Download:
http://www.123dapp.com/

Learn:
http://www.123dapp.com/SiteFiles/Support/Designing_with_123D_Beta5.pdf

Another very nice program, within the same family of 3D tools, is Autodesk 123D Catch. You can find it on the same page as the download link above. Catch allows you to turn your photographs into 3D models. How cool is that?