Paul,
You have had many readers asking about 3D drawing software. Because I
am planning to purchase a 3D printer I too have been looking for a
suitable 3D CAD program.
I found one that I believe will work nicely for the majority of your
subscribers. It is called Design Spark by RS-Online. _RS_ Components
is the leading distributor of Electronic, Electrical & Industrial
components in the UK . They offer two FREE versions: Design Spark
Mechanical and Design Spark PCB (electrical).  Both programs are
designed for non-engineers so the interface is very intuitive. I am
not an engineer and I have no CAD experience, but I was able to draw
and manipulate a 3D object in 30 minutes. There are many tutorials
available on their website as well as a user manual.

http://www.rs-online.com/designspark/electronics/eng/page/mechanical
I prefer the many tutorials on YouTube as they load faster and there
are more to choose from.  Just search for "Design Spark Mechanical
tutorials".
I had my son who is a mechanical engineer and fluent in Solidworks
have a look at both Rhino and Design Spark and he thought Design Spark
would work well for me as the interface was more intuitive than Rhino.
He said Rhino has more capabilities for the serious user, but Design
Spark should work fine for most projects.
Cole T. Chandler

PS  I have been following your website for several years and am a
believer in your cause. Your efforts have and will continue to bring
us closer to widespread acceptance of the rotary engine as the
powerplant of choice for aircraft.



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