Alright, let's get started! Open up your Figma project, or if you're feeling adventurous, create a new one. This is where we'll set up our custom breakpoints for responsive design.

Time to create some frames for the devices you're designing for:

• Grab the Frame Tool (F).
• Draw frames for different device sizes like mobile, tablet, and desktop.
• You can also use the handy presets in the frame tool dropdown for common device dimensions.

• Pick a frame you want to make responsive.
• Click on Auto Layout in the properties panel or just hit Shift + A. Auto Layout is your friend for creating flexible and responsive layouts.
• Tweak the padding, spacing, and alignment options under Auto Layout to fit your design needs.

Let's add some guidelines to mark where your custom breakpoints will switch:

• Drag rulers from the top and left to create fixed points.
• Place these rulers at pixel dimensions that match your breakpoints (like 768px for tablets).

Now, design different versions of your layout for each breakpoint:

• Duplicate your main frame for different breakpoints (Ctrl + D or Cmd + D).
• Adjust elements within each frame to fit the corresponding device screen sizes.
• Make sure text, images, and other assets resize or rearrange according to the specific breakpoint needs.

Keep things tidy:

• Arrange frames in a logical order from smallest to largest.
• Group relevant layers and use naming conventions for easier identification.
• Use components and variants for elements that need to be reused across different breakpoints (like navigation bars).

Check responsiveness across frames with Smart Selection:

• Hold down Shift and click on elements across different frames to select similar items.
• Adjust sizes and positions in Smart Selection mode to ensure consistency and responsive behavior.

Let's create a prototype to see the breakpoints in action:

• Switch to the Prototype tab.
• Link frames to simulate navigation between different breakpoints.
• Use the “Resize to fit” option within the prototype settings to allow the frame to adjust according to its content at different sizes.
• Navigate through the prototype to ensure all breakpoints look consistent and functional.

Share your design with stakeholders or team members:

• Click on the “Share” button to generate a link.
• Gather feedback and iterate on the design as necessary to ensure all breakpoints are handled effectively and the design remains consistent across devices.

Finally, export your assets for development:

• Select the frames or elements you wish to export.
• Click on the “Export” option in the properties panel.
• Choose the appropriate formats (like PNG, SVG, JPEG).
• Make sure you export at multiple resolutions if needed for responsive web design (like 1x, 2x for retina displays).

This method ensures you fully leverage Figma's capabilities to design and prototype responsive layouts effectively using custom breakpoints.