Revise and expand OpenAT Design Guide introduction

Rewrites the introduction to clarify what Open Assistive Technology (OpenAT) is, the purpose and audience of the guide, and how the guide is organized. Adds sections for context, improves readability, and emphasizes the guide's evolving nature and collaborative approach.

Author: jakemcivor

index.md

@@ -5,15 +5,41 @@ layout: home
 
 # OpenAT Design Guide
 
-Many of the devices in the MMC library use the same components, but all use slightly different dimensions when adding the parts into the design. The designers frequently reference other, older designs that use the part for the correct dimensions to use, but there are so many different dimensions used that this leads to several different ‘standards’ being used across devices for the same part. This guide is an attempt to standardize the dimensions for parts across designs, and to serve as a central reference point for use designing devices. 
+## What is Open Assistive Technology (OpenAT)?
 
-In the Commercial Components section, the guide covers the commonly used commercial parts in MMC designs, and how to integrate them into 3D printed components. This includes the right size holes to use for screws, the best ways to secure a switch to a component, and what size openings to use for various USB connectors. 
+Open Assistive Technology (OpenAT) refers to assistive devices whose designs are publicly shared so that anyone can study, make, modify, and improve them. OpenAT projects are typically co-created by people with disabilities, engineers, makers, and disability professionals.
 
-The Design Elements for 3D Printed Parts section covers common design elements used in MMC devices, such as 3D printed threads, cotter pins, and shadow lines. This section focuses less on exact measurements and dimensions than the previous section, as the designer has control over the dimensions of all the components involved. Instead this section focuses more on the necessary design considerations and minimum/maximum sizes of the features.
+Because the designs are open, these assistive technologies can be:
 
-The 3D Printing Design Tips section of the guide links to other 3D printing design guides that cover wall thicknesses, overhangs, optimizing for print speed and material usage, and filet sizes while breaking out the section on printing overhanging holes from the Hydra Research design guide for easy reference. It also gives a brief overview of the printers used in the design of the devices mentioned in the guide, and how that affected the tolerances used in the guide. Finally, it covers how these tolerances can be changed for other 3D printers to make them fit better.
+- Adapted to individual needs  
+- Built locally at lower cost  
+- Improved collaboratively by a global community  
+
+## What is the OpenAT Design Guide?
+
+The OpenAT Design Guide is an evolving collection of practical resources and best practices for designing open assistive devices that are easy to build, adapt, use, and improve upon. This guide is an attempt to standardize the dimensions for parts across designs and to serve as a central reference point for people designing devices. The guide is a living document, intended to be changed and updated as better measurements and new design techniques are developed by the Makers Making Change team and the wider community.
+
+## Who is this guide for?
+
+This guide is for anyone who designs assistive technology intended to be built as a do-it-yourself (DIY) or do-it-together (DIT) project, or build by volunteer makers. 
+
+
+## How this guide is organized
+
+- **Commercial Components** – Recommended dimensions and mounting methods for common parts used in OpenAT and MMC designs (e.g., screws, switches, USB connectors, etc.).:contentReference[oaicite:3]{index=3}  
+- **Design Elements for 3D Printed Parts** – Patterns like screw posts, snap fits, shadow lines, and strain relief, with design considerations and typical min/max dimensions.:contentReference[oaicite:4]{index=4} 
+- **3D Printing Design Tips** – Links to trusted 3D printing design guides and explains how printer choice and settings affect tolerances used in this guide.:contentReference[oaicite:2]{index=2} 
+
+Additional sections will be added as this resource grows.
+
+In the **Commercial Components** section, the guide covers the commonly used commercial parts in MMC designs, and how to integrate them into 3D printed components. This includes the right size holes to use for screws, the best ways to secure a switch to a component, and what size openings to use for various USB connectors. 
+
+The **Design Elements for 3D Printed Parts** section covers common design elements used in MMC devices, such as 3D printed threads, cotter pins, and shadow lines. This section focuses less on exact measurements and dimensions than the previous section, as the designer has control over the dimensions of all the components involved. Instead this section focuses more on the necessary design considerations and minimum/maximum sizes of the features.
+
+The **3D Printing Design Tips** section of the guide links to other 3D printing design guides that cover wall thicknesses, overhangs, optimizing for print speed and material usage, and filet sizes while breaking out the section on printing overhanging holes from the Hydra Research design guide for easy reference. It also gives a brief overview of the printers used in the design of the devices mentioned in the guide, and how that affected the tolerances used in the guide. Finally, it covers how these tolerances can be changed for other 3D printers to make them fit better.
+
+Finally, there is a **How to Contribute** section that covers how to make changes to the guide or add new sections. This guide is a living document and intended to be changed and updated as better measurements and new design techniques are used, both by the Makers Making Change team and community.
 
-Finally, there is a How to Contribute section that covers how to make changes to the guide or add new sections. This guide is a living document and intended to be changed and updated as better measurements and new design techniques are used, both by the Makers Making Change team and community.
 
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