10 Best Places to Buy Parts for Product Development

By Josh Siegel

Purchasing off-the-shelf components is an essential task when developing mechatronic systems, especially for prototyping and low-volume applications. Often, the availability and price of particular off-the-shelf components inform the design. 

For example, if I'm designing a system that requires a dowel pin, I should try to pick a type and size of dowel pin that is inexpensive and available for purchase. How do I know if it's inexpensive and available? If I don't already know it from experience or intuition, then I look online and search through a company's website where I would expect to find that part.

Searching for off-the-shelf components becomes more efficient with repetition and learning which places specialize in specific components. As a mechanical engineer designing mechatronic systems, I have my go-to websites to look for off-the-shelf components. If you are in the same field, you’re likely familiar with these places. If you have any go-to places of your own, other than what I’ve listed here, please feel free to let us know!

1. McMaster

McMaster is commonly the first stop for mechanical components for prototyping and low-volume applications. Mechanical engineers pray that there’s a heaven that is as beautiful as the McMaster catalog. It is the mecca of parts, and the site is incredibly user-friendly. McMaster provides multiple forms of 3D CAD for a good deal of parts including screws, 8020 components, and bearings, which is appealing for mechanical engineers.

2. Digikey

Digikey does for electrical engineers what McMaster does for mechanical engineers. Digikey items are usually listed with different prices based on the quantity, so it can be helpful for gauging how much components will cost in both low-volume and medium-volume productions. Digikey also gives you the manufacturer’s part number for most parts, so if you can’t find the information you need on the Digikey page, navigate to the manufacturer’s webpage and search for the part directly.

If you can’t find what you’re looking for on Digikey, it may be worth looking at Mouser (generally not as user-friendly as Digikey, but can be less expensive). Kristin, an electrical engineer here at Simplexity, also recommends Octopart, FindChips, and for electronic components.

3. ThorLabs

ThorLabs is great for experimental applications, particularly with optics and optomechanics. ThorLabs’ optical breadboards and linear stages can be used in a diverse set of applications. Newport also has nice linear stages, and Edmund Optics is another great place for optics.

4. Misumi

Misumi, like McMaster, has a wide variety of parts. Check out their impressive array of dowel pins and fasteners, and take note of their collection of mounting plates and brackets, which could potentially replace a machined component in an assembly. Misumi’s inCAD Library can be a great resource for mechanism design.

5. Amazon

If you’re looking for a part that can be categorized as a consumer product, then it’s likely that Amazon will have it, and it’s likely that it will be cheap. Unlike many of the others on this list, Amazon seldom gives thorough technical information about their parts, so be cautious.

6. McMaster

Did I mention McMaster? I’m mentioning McMaster again. This is not a paid post, they just deserve an extra emphasis.

7. Sparkfun and Adafruit

Sparkfun and Adafruit fall under the same category for me. They have a great deal of products for easy electronic prototyping, and their websites are very user-friendly. Sometimes they’ll give you thorough technical information and provide complete datasheets for their parts, but it’s not a given.

8. Omega

Omega’s specialty is sensors. Instrumentation and sensors can be expensive, but Omega’s products are typically very robust and come with all the necessary information to use them effectively. Keyence is another great provider of sensors and instrumentation.

9. Penn Engineering

More commonly referred to as PEM, Penn Engineering specializes in fasteners for sheet metal.

10. SDP/SI and igus

SDP/SI, also known as Stock Drive, is a fantastic source of small mechanical components involved in driving motors. At igus you’ll find many plastic parts for linear motion.

Of course, these are only the first-stop places for off-the-shelf components, in general. Often times these places won’t be specialized enough for the type of part we need (e.g., custom motors, specialized springs) and we’ll look elsewhere. During the design process, if we are unable to find a great off-the-shelf solution, we will either change the design, find an in-house solution, or work with a vendor to create a custom solution.

By knowing how to design with off-the-shelf parts, Simplexity can cast an even wider net to assure that each project gets precisely the components it needs. Part of our expertise is knowing where to look.

For any questions related to part selection or any other topics, please contact us at




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