Bill Schnoebelen, 4/11/2017

“Any problem can be solved using the materials in the room.” Edwin H. Land (founder of Polaroid Corp.)

Get it out of CAD ASAP! Prototypes and mock ups are crucial for a design. They are where the rubber meets the road. You should plan at least a simple test of every critical feature.

Prototyping, however, can bring its own problems. I view prototyping as identifying and solving your problems before they multiply in production. Prototyping iterations and testing leads to a better product. This is why we built a room around prototyping.

Below is a short summary of how we go about prototyping. I also added how we take it into production since that is the end goal of most designs.


Extrusions can be prototyped using CNC machining while thin cross sections can be prototyped using water-jetting.

In the past, we have developed slides on a mill to index and prototype very long extrusions (+2 meters). For the cost, it may be much simpler to build a tool, but we were in a hurry at the time. The milling allowed us to quickly try different configurations with real parts. These were very complicated extrusions.

For production, extrusions tools are typically inexpensive and reliable if designed correctly.

Sheet Metal

Sheet Metal Tools

Sheet Metal Tools

A very simple way you can prototype sheet metal is with  duct work tools and thin gauge sheet metal. This gives you a quick/simple way to test heat and EMI. Two things which can come back to bite you in the ass.


Sheet metal manufacturing equipment is expensive and large. We don’t do prototyping beyond hand mockups. We do have some excellent reliable local sources. Their extensive knowledge in sheet metal is very beneficial to a successful production design. We have certainly pushed the envelope with them.

Sheet metal fits in well with volume production. We have good sources of sheet metal suppliers locally for low to mid volume. Tooling can be made to simplify the process overseas as volumes ramp up.


For roughing in and sharing the concept we use simple 3D prints. This gives stake holders a good rough estimation of how it will look and how it will go together.

machined and polished plastic parts

Machined and Polished PMMA (Acrylic)

For fine tuning we machine the components. The reason is both the surface finish and dimensional stability are much better. We tried several 3D printing technologies, but they fell short. Additionally the properties of the materials are better known. We are dealing with homogeneous materials such as ABS or PC.

We design each part iteration for the process for which it is being made. We have both in-house 3D printing and machining capabilities. We can make more iterations in a shorter period of time. Once the mill is setup, we can run several serial iterations often within a few hours.

For production, we can source molds and molders both overseas and locally. The mold lead times have come down due to advancements in CAM and milling technology.  Proper design and good communication are critical for a quality product. I can’t say enough about having a good molder who can fine tune.

Machined Parts

We have extensive knowledge of machining, setups, programming, tooling, and materials. As the owner of the company, I stress the machining. It is the core of mechanical engineering.

Machined Part

Machined Part

I have seen too many problems get thrown over the wall. My philosophy is that if the engineer is machining the part, the engineer will figure out the least amount of time to machine it. This reduces cost. DFM is not an afterthought.



As mechanical engineers we typically make 3D prints of PCBs. This is just for a rough mockup.

There is an extensive list of capable PCB manufactures in the Bay Area. Some have specialties such as flex circuits. For medical devices, we work with local assembly houses who have medical compliance. For consumer products, we work with local and overseas vendors who can handle the boards, assembly, and compliance.


Hell yeah.

Tig Weld

Tig Weld

How We Do It

Edwin Land was most certainly talking about proof of concepts. Higher costs and imperfections in a proof of concept are acceptable. In a production product, these mean failure.

At Circuit Case Engineering, we built a room specifically for prototyping. We have manufacturing equipment specifically for prototypes. We solve problems at the mill. There is no hiding in a cubicle and throwing it over the wall. Our designers are the same folks who run the machines. Simplicity and functionality are inherent into the system.