This project milestone will require students to practice the following SolidWorks skills:

Extrudes (boss and cut), Shell, Sketch Relations, Convert Entities, Linear Feature Patterns, Equations, and Global Variables.`Students must create a 6x2 black block similar to LEGO part number 379521 (see last page of your LEGO kit documentation). The block must be created according to the following, and in this order. Save your original SolidWorks part file to your project folder on the W drive, called "skinnybrick." The file type should be SLDPRT (*.prt; *.sldprt).

1. Create global variables "Length" and "Width" and set Length=6 and Width=2.

2. Create the base extrude feature, based on a sketch where the length and width are defined using an equation referencing the two global variables already defined in Step #1 and multiplying by 8mm to calculate the total width and length of the block. Place your sketch on the "top" plane for this base feature and be sure to extrude "up". Extrude the sketch to 3.2mm.

3. Create one circular knob feature, with diameter of 5mm and height of 1.8 mm. Locate the center of the boss 4mm each direction from the corner of the base feature.

4. Create a linear feature pattern in two dimensions, using the edges of the base feature to define the direction. Set the spacing to 8mm and set the number of instances in each direction by using equations to reference the two global variables already defined in Step #1

5. On the bottom of the base feature, use the shell command to create a shell feature with a thickness value of 1.5 mm.

6. Adjust the depth of the hollow under the LEGO by doing another extrude cut that is 0.1 mm deep. This makes the depth 1.8 mm instead of 1.7mm (so the LEGO blocks would fit together properly).

7. Create a sketch on the underside (same face you just adjusted in step 6). Use "convert entities" to bring the four circular edges of the bosses into your sketch. Select the four circles in your sketch and make them construction geometry (dashed lines). Now create an annulus (circle inside a circle, concentric) such that the outside circle is tangent to the dashed circles (only need three tangencies to define) and the inside circle has a diameter of 5mm.

8. Notice that you don't have enough of the annulus bosses on the underside. Fix this by creating another linear feature pattern in two directions, using an equation to link it to the "Length" and "Width". Hint: Remember that you need to use an "n-1" approach...there are always one less ring underneath in each direction compared to the number of knobs on top.

9. Try redefining "Length" and "Width" to be other values. Note that your patterns work well so long as there is more than one new instance of the feature. For instance, if you set Length=2 and Width=2 you will get an error because the pattern for the ring underneath no longer has any new instances. The solution to this problem is to "suppress" the pattern when it is not being used ("suppress" is available when you right-click a feature in the tree).