## Introduction: Design a Mini Whistle in 123D Design

Make a mini whistle to keep in the tiny pocket of your jeans that you never use. It's small, fun, and can easily be designed and printed in under half an hour.

I made this because I volunteer at a makerspace and I wanted to show people how easy it could be to design something themselves. While this isn't the most efficient design method, it's good for beginners because it allows for the use of a variety of tools.

The largest whistles pictured are the actual size of the one designed in this tutorial. I also printed smaller whistles; I think the smallest pictured is 70% of the original size. They all work well.

This tutorial uses the following basic functions of 123D Design:

• Change View using View Cube
• Zoom
• Pan
• Sketch a Circle
• Sketch a Rectangle
• Extrude (Merge)
• Shell
• Sketch a Polyline
• Move
• Extrude (Subtract)
• Fillet
• Merge

As well as a few other functions that require the use of shortcut keys:

• Copy (Ctrl + C)
• Paste (Ctrl + V)
• Drop on Grid (select solid/mesh + D)
• Flip About Grid (select solid/mesh + spacebar)

## Step 1: ​Top View

Objective: Use the View Cube to set the camera to top view. Try panning and zooming in/out.

The View Cube is located in the upper right hand corner of the window.

1. Select the face of the cube labeled ‘TOP’.
2. Place the cursor at the bottom left hand corner of the grid and use the scroll wheel up to zoom in, scroll wheel down to zoom out. The camera will zoom in on the location of the cursor.
3. To pan across the grid: Press and hold the scroll wheel + drag mouse.
4. Zoom in and pan so that the screen shows a 50 mm x 50 mm section grid in the center of the screen.

To reset view: Click the little house that appears when you move the cursor over the View Cube.

Once you have an object on the grid, you can select that object and press ‘F’ to fit the object the screen.

## Step 2: ​Circle Sketch

Objective: Use primitives from the Main Toolbar to create a circle sketch that is 16 mm in diameter. Create the circle in the bottom-left hand corner of the grid.

From the Main Toolbar:

1. Sketch > Sketch a Circle
2. Click anywhere on the grid to specify center of circle.
3. Set diameter to 16 mm (Two methods to set diameter)
• drag and click
• input value and then press 'Enter'
4. Press ‘Enter’ to exit tool.

## Step 3: ​Rectangle Sketch

Objective: Use primitives from the Main Toolbar to create a 20 mm x 5 mm rectangle sketch. Place first corner of the rectangle centered at the top of the circle.

From the Main Toolbar:

1. Sketch > Sketch a Rectangle
2. Move the cursor over the circle.
3. Click to edit sketch.
4. Specify the first corner of the rectangle: centered at the top of circle.
5. Move the cursor up and to the right until a rectangle appears. Boxes will also appear where you will be able to input the dimensions of your rectangle.
6. The box for length should already be highlighted. Input ‘20’.
7. Press ‘Enter’ to set the length.
8. The box for height will now be highlighted. Input ‘5’ as the height.
9. Press ‘Enter’ to set the height.
10. Press ‘Enter’ to exit tool.

## Step 4: ​Extrude

This is the step where the design will go from 2D to 3D.

Objective: Change view to TOP-FRONT. Extrude sketches 5mm.

1. Use the View Cube to change the view to TOP-FRONT. Choose the view that highlights the bottom edge of the ‘TOP’ face and the top edge of ‘FRONT’ face.
2. From the Main Toolbar:
1. Construct > Extrude
2. Select a 2D shape or face of a solid to Extrude: Click on each piece of the circle and rectangle until they are all dark blue (if needed, press ‘F’ to fit the object to the screen).
3. Two methods to Extrude:
• Drag the arrow up to extrude the whistle 5 mm
• Input value
4. Press ‘Enter’ to exit tool.

## Step 5: ​Make It Hollow

This step will make the whistle hollow.

Objective: Select the top face of the whistle. Shell, set thickness inside to 2 mm.

1. Select the top face of the whistle.
• To select a face, click on the object and then click on the face you want to select. The face will turn dark blue once It has been selected. If you keep clicking and the face still isn’t being selected, click on a different face and then go back to the face you originally wanted and try selecting it again.
2. From the Main Toolbar:
1. Modify > Shell (Two methods)
• Drag the arrow up to 2 mm.
• Input value.
2. Press ‘Enter’ to exit tool.

## Step 6: ​Extrude (Subtract)

1. Select the face of the whistle where the hole for the mouthpiece should be (you can see it from the TOP-RIGHT view).
2. From the Main Toolbar:
1. Construct> Extrude
2. Move the arrow in towards the whistle (you will see a red box) until it reaches a place in the whistle where the hole is exposed, or input ‘-2’ as the value.

## Step 7: ​Triangle

Create a triangle that will be used to cut out the hole at the top of the whistle.

Objective: Use Polyline tool to create a right triangle with a base of 5 mm and a height of 5 mm.

Change to appropriate top view; from the Main Toolbar:

1. Sketch > Create a Polyline
2. Click on grid.
3. Click to specify first point.
4. Move 5 mm to right, click to specify next point.
5. Move 5 mm down, click to specify next point.
6. Move cursor back over first point, click to specify next point.
7. Press ‘Enter’ to exit tool.
8. Use the Extrude tool to extrude the triangle 5mm.

## Step 8: ​Move the Triangle

Objective: Move the triangle so that its bottom-right vertex is almost touching the inner part of the whistle where the body and the mouthpiece converge. Move the triangle up 2 mm along the z-axis.

1. Keep the camera view at TOP view, but zoom and pan if necessary; use any of the methods listed below to:
• Move the triangle to the appropriate position. Drag method will work best for this.
2. Once the triangle is in place, change the view to TOP-FRONT view and use the Move / Rotate tool to
• Move the triangle up 2 mm along the Z axis.

There are several ways to move an object.

1. Drag: Press left-mouse button and drag. When you are finished moving the object, release button and click outside of object to exit tool.
2. Arrow keys: Select object, use arrow keys to move object into place, click outside of object to exit tool.
3. From the Main Toolbar:
1. Transform > Move / Rotate.
2. Select object.
3. Three white arrows will appear that will move the object along either the X, Y, or Z axis. Select the appropriate axis and use the arrow to drag the object along the axis. Or, input a specific value.
4. Click outside of object to exit tool.

## Step 9: ​Make the Hole

Objective: Subtract the triangle from the body of the whistle to create a hole.

From the Main Toolbar:

1. Combine > Subtract
2. Click the whistle to select the whistle as the target.
3. Click the triangle to select the triangle as the source.
4. Press ‘Enter’.

## Step 10: ​Copy, Paste, Flip

Create the other half of the whistle.

Objective: Copy and paste the object we have created (half of a whistle). Flip it about the grid and move it to create a whole whistle.

1. Select the object.
2. Ctrl + C to copy.
3. Ctrl + V to paste.
4. Click anywhere on the grid, to deselect the object.
5. Click on the object to select it.
6. Press Spacebar to flip about grid.
7. Use the Move / Rotate tool to move the flipped half up 10 mm so that it sits on top of the original piece.

## Step 11: ​Merge

Create one object from two separate pieces.

Objective: Select and merge all objects.

1. Combine > Merge
2. Click the bottom half of the whistle to select it as the target.
3. Click the top half of the whistle to select it as the source.
4. Press 'Enter' to execute command.

## Step 12: Smooth an Edge

Objective: Use ‘Fillet’ to smooth an edge.

1. Change view to TOP-FRONT-RIGHT view.
2. Select the edge at the bottom part of the whistle where the mouthpiece and body meet.
3. A little gear will appear
4. Hover over the gear
5. Select Fillet
6. Use the arrow to set the fillet radius to '4' or just input the value.
7. Press 'Enter' to execute command.

## Step 13: Some Finishing Touches

The whistle looks great, but there's a little extra material that we can get rid of. The side walls are a little thick and can be taken in 1 mm to save plastic and print time.

1. Select the top face of the whistle.
2. Use the Extrude-Subtract method that we used to cut the mouthpiece to bring it in 1 mm. Do the same for the face of the whistle that is against the grid.
• The side against the grid is easier to see from BOTTOM view.
• The sketches might get in the way, so Select + Delete/Backspace to delete them.
3. Since 1 mm was removed from the bottom, the whistle will now be floating 1 mm above the grid.
• Select the whistle and press 'D' to drop the whistle back into the grid.

## Step 14: Save

1. Go to the Application Menu (upper left) > Export as 3D > STL (other formats also available)
2. Select 'OK'
3. Name and Save