monetizing open designs for 3d printed parts

Current state

There's a lot of talk about unrealistic DRM schemas for 3d printed designs.
Mostly centered about limiting the ability to print replacement parts by putting DRM on the design files. ...and forgetting that the original design files are never published but instead reverse engeneered using screwdriver and caliper.

There's also a lot of talk about selling the right to print a published design (a bad and unrealistic idea) and about the selling of physical manifestations of designs instead.

We've had small CNC machines in above-average hobby-workshops for years now.
Particularly in the model-building works these are common and parts made in these hobby-workshops are regularly sold.
Personally I don't think that the world will suddenly collapse just because a new kind of CNC device that is less dirty and produces plastic instead of wood and metal arrives.
Parts still need bolts, bearings, electronics, labeling, painting, ... . There is no reason to believe that any design consisting of only one plastic part with no regards for material and tollerances (in the case of selling a DRM-controlled right to print a design) is of particular relevance or importance.

The experiment

So I'd like to try something.
I published quite a few designs under CC-BY-NC(-SA).
Due to the -NC part I'm the only one allowed to monetize them. Sell them, advertise with them, sell physical copies.
So I'm posting some parts that I find useful to a general public on eBay.

1. The designs are still CC and published, so everyone is free to print them for themself.
2. Everyone is also still free to ask someone else to print them and they can even charge a fee for the service of printing.
3. I only sell physical objects after they are printed and tested and found to be of good quality.
4. I include required non-printed parts and may even go so far as to do some simple packaging and instructions. 

 Expected results

 

I don't expect many items to be sold at all.
I expect the need to brush up my skills of presenting the parts in a more professional way in order to actually sell some.
Prices will probably stay very reasonable (1-5eur, maybe more).
I expect a more practical discussion about licenses, where we want the world to be headed and where it will be headed regarding open designs and personal 3D printers.

• My first eBay auction
• Blog posting about my choice of creative commons licenses
• example of third parties selling a non-NC design
• My Google+ posting