A structural enclosure design for a set of binoculars
we have developed an original mechanism of switching magnifications with a reliable lens system drive
We reduced our client's costs by combining multiple plastic parts in the same mold
A structural enclosure design for a set of binoculars
we have developed an original mechanism of switching magnifications with a reliable lens system drive
We reduced our client's costs by combining multiple plastic parts in the same mold

Binoculars with Discrete Magnification

Project Overview

We developed the design and structural layout of an enclosure for binoculars with a discrete magnification power of 2.5:5, as well as manufactured its prototypes and set up production in China. Potential users of the product: fans at sports stadiums, spectators and participants of mass events in open areas.

Our designers and industrial designers met the customer's basic requirements for the product's ergonomics and colors: the device sits comfortably in your hands, has bright coloring and features a special spot for a logo. While working on the enclosure design, we also implemented splash protection.

Key characteristics of the developed enclosure:

  • An original diagram of the variable magnification of the binoculars: pushbutton operation; finger pressure is transmitted to the axle which rotates the lens system and changes the magnification power
  • Minimum manufacturing cost (it is a low-end product): most of the binoculars components are made of plastic. Basic parts: plastic ABS; load-bearing parts: polyamide plus 10 per cent glass; the most important parts: metal
  • Binocular eyepieces and controls are covered with special rubber-coated soft-touch coating
  • Easy manufacturing and assembly: some plastic parts are cast in the same mold, and the product is assembled without fastening screws

Project outcome

Under the project, Promwad experts completed the following tasks:

— Selection of materials for the enclosure
— Structural design of all the parts
— Development of tooling for mass production (set of molds) 
— Manufacturing of prototypes
— Setting up production in China







How It's Made


The objective is to create a structural design for a set of binoculars with a discrete magnification power of 2.5:5.

The binoculars are designed for watching sports and other public events in stadiums, open areas and large enclosed spaces in the afternoon and in the coming dusk. The product lies within the lower price range. The binoculars should meet the following criteria:

  • Sitting comfortably in your hand
  • Bright colors
  • A special logo spot

The product’s dust and water resistance requirements, based on the price category, did not require complete sealing of the product. The only special feature the device needed was splash protection.

The product’s original optical circuit influenced the engineering solutions. The problem was that the binoculars had variable magnification. A magnification switching circuit was included in the specifications.


As the hardware platform was selected USB smart drive by SanDisk supporting U3 technology. SanDisk Extreme Contour is an extremely rugged and smart USB flash drive. It is built with Liquidmetal® casing that is crash-resistant to over 2,000 lbs. SanDisk Extreme Contour also includes U3 smart technology which deals with security functions

1. Design

The magnification switching mechanism and compact size of the product determined its exterior. Its small size with rounded forms lent it a special charm and appeal.

After a preliminary study of the design options allowing for a magnification switching mechanism, the customer chose the following option:

2. Structure 

After we examine the customer’s option for the mechanics of switching magnifications, we developed an absolutely original mechanism based on the pushbutton function of transferring pressure from the thumb to the lens system rotation axis, thus changing multiplicity. The original design helped reduce the risk of breakage of the lens system drive mechanism and switch multiplicity without taking the product away from the eyes.

The lower price category products required a maximum of plastic parts. That is why only the most important parts included in the product design are made of metal.

Major bearing parts of the enclosure are made of ABS plastic. The load-bearing parts are made of polyamide with 10 per cent glass filling.

3. Start of Production 

The development of molds for casting plastics involved the steps to reduce the cost by combining multiple plastic parts in the same mold. The manufacturing process used two types of plastics: ABS plastic for outer enclosure parts and polyformaldehyde for inner structural parts which perform an executive function and require high durability.

All plastic parts are painted in mass. Generic outer parts are given RAL numbers for the same color to ensure repeatability in batches. Inner structural plastic parts are painted black to eliminate glare. Aluminum anodizing help make the product’s aluminum parts identical to black plastic.

To improve tactile sensation and give the binoculars a strict look, the eyepieces and controls (focus wheel and magnification switch buttons) were coated with a soft-touch paint.

The production stage involved the use of five molds for plastic parts.

Promwad’s trusted partner in China was selected to provide a production site and was able to implement the project in keeping with specified quality, time and cost parameters.


  • Low cost of a set of enclosure parts in batch production
  • Ease of assembly: no screws for fastening the whole device
  • Sophisticated ergonomics: the product is easy to work with to the touch
  • Low cost of a set enclosure parts in comparison with analogues
  • The devices are designed to meet all the customer’s requirements
  • The customer can change the color of enclosure parts in each batch or get multiple colors of choice in the same batch


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