Kids Code & Computer Science

Bring out your virtual carving knives — it’s time to give your digital pumpkins some spooky faces!

SketchUp is a free and fun program for 3D modeling. You can use SketchUp to design just about anything, from furniture to a dream bedroom to an entire city.

The free, web-based version of SketchUp can be found online at https://app.sketchup.com/app.

With Halloween around the corner, let’s model this jack o’lantern!

This project has two parts: modeling the pumpkin itself, and adding the face to it.

When you start modeling in SketchUp, you start in this view, with Helen standing on the ground. She isn’t needed in this model, so press E for the Eraser, and click on any of Helen’s edges.

Press C for the Circle tool, click the origin (where the three axes meet) to place the center, and draw a circle of any size on the “ground.”

We need one more circle. While still in the Circle tool, tap (don’t hold) the Left or Right arrow, which orients the circle to be vertical For this circle, place its center at the origin as before, and make this circle a bit larger than the first one.

We’ll use these two circles to make a sphere. Press the Spacebar for the Select tool, and click the smaller circle to select it.

Then open the Push/Pull flyout toolbar and click the Follow Me icon.

Click the larger, vertical circle.

Follow Me spins one circle around the other, producing a sphere.

This sphere will be copied several times, and all copies need to be identical. Components are perfect for this – when you make changes to one component, you change all of them the same way. So with the Select tool active (Spacebar), triple-click (yes, three times quickly) the sphere. Then right-click on the sphere and choose Make Component.

Give the component any name you like, and press Enter or click OK.

Now the entire component is a single object, with a blue bounding box surrounding it.

This sphere will be used for rotate-copying. Keep the sphere selected, and press Q for the Rotate tool. Move the protractor along the red axis, not too far from the sphere, and click to place it.

Now tap the Ctrl key (PC) or Option (Mac), so that copies will be made. Move the mouse away from the protractor, and click anywhere to set the “zero” angle. Then start to pull out the copy, and type the number 45. This degree value appears in the Angle field at the lower right corner. You never have to click inside this field – just type and the numbers appear. Press Enter to complete the first copy.

To get copies all the way around, type 7x and press Enter.

Now the spheres have to be moved closer together, and their overlapping outer faces will form the outside of the pumpkin.

With the Select tool, double-click either of the two spheres that sit along the red axis. This opens the component for editing.

Then click the sphere, to select it.

Press M for the Move tool. The move direction can be set by clicking anywhere for the first point, then move your mouse in the red direction. Whatever you do to the sphere being edited is done to the other components as well. So as all of the spheres move inward, click to finish when the overlap looks something like this:

Go back to the Select tool, and click anywhere in blank space to finish the component editing.

That first circle is still there at the origin, and it can be erased.

The eight sphere components no longer need to be components. While in the Select tool again, press Ctrl + A (PC) or Cmd + A (Mac) to select everything. Then right-click on any selected sphere and choose Explode.

It may take a few seconds to complete, but after exploding, the spheres are all selected. Leave them selected.

Open the Materials window with the icon on the right side. Click the Browse icon (the magnifying glass) to open the material collections, and open Colors.

Find an orange color you like (or whatever color you want your pumpkin to be), and click any selected face of the spheres. All selected faces get painted at once.

Now it’s time to add the face. We’ll first create a box on which we’ll draw the facial features. So orbit your view so that you’re looking straight down at the top of the pumpkin. Press R for the Rectangle tool and draw a rectangle on the ground that’s approximately the same width as the pumpkin.

The rectangle is at the middle of the pumpkin, so it needs to be pulled up and down. Press P for the Push/Pull tool, and click the rectangle. Click again anywhere on the top of the pumpkin.

Then orbit to see the bottom of the box, and pull down the bottom to the level of the bottom of the pumpkin.

The front of this box is more or less the same size as the front of the pumpkin. So with the Line tool (press L), draw triangles for the eyes, and some jagged lines for the mouth. Be sure that all three shapes are closed loops.

Now erase all parts of the box except for the three shapes.

With Push/Pull, pull each shape back toward the pumpkin, stopping anywhere inside the pumpkin.

The goal now is to get intersection edges where these three shapes meet the front of the pumpkin. Using Select, draw a selection window like this one, going from right to left. As long as this selection rectangle includes all of the front faces and any parts of the side faces, all of the necessary faces will be selected.

Right-click on any selected face and choose Intersect Faces / With Model. Again, this might take a few seconds to process – there is a lot of geometry here!

After erasing all of the white faces that stick out of the pumpkin, what should remain are edges along the front of the pumpkin.

Find a dark color, and paint all of the bits of these small faces. Done!

Learn More

Haunted house

https://www.youtube.com/watch?v=29hz3zJg_FI

Pumpkin in Sketchup

https://www.youtube.com/watch?v=SERjyXdfwaw

Scrollsaw patterns

http://www.woodworkersworkshop.com/resources/index.php?cat=163