Simple Box Cover

Introduction
This short tutorial will explain how to model a simple box cover with engraved text. The cover will have a flat top with a lip all around to fit over a box.

The context: you have downloaded a sorting box model from a popular "things" sharing site, and you have printed it with your personal 3D printer. It's perfect to sort your bolts, but you would like to have a cover to go with it, with "Bolts" engraved on top of it so it's easy to recognize among your many other printed boxes!



For this we will use the Draft, Part and Part Design workbenches.

The sequence of operations will be:
 * 1) Create a sketch and draw and constrain a rectangle
 * 2) Create a Pad feature out of the sketch
 * 3) Hollow out the Pad solid using the Part Thickness tool
 * 4) Create text on top of the cover using the Draft ShapeString tool
 * 5) Create a PartDesign Pocket feature using the Draft ShapeString object.

Figuring out the dimensions
Let's say that the box length and width are 110x110mm. We should allow some play between the box outer dimensions and the cover inner dimensions, so let's add 1mm on each side. We want the cover to be 3mm thick, and the lip to be 7mm high without counting the top.


 * Cover inner length: 111mm
 * Cover inner width: 111mm
 * Cover thickness: 3mm
 * Cover lip height: 7mm

Making the base solid
We will make a base solid of which dimensions equal the empty volume inside the finished cover.

Creating the sketch

 * 1) Start FreeCAD, create a new document and using the workbench selector, switch to the Workbench_PartDesign.svg PartDesign Workbench.
 * 2) Click on the Sketcher_NewSketch.png Create new sketch icon in the toolbar.
 * 3) In the "Choose orientation" dialog, select the XY-Plane and click OK.
 * 4) Click on the Sketcher_CreateRectangle.png Create a rectangle icon.
 * 5) Click somewhere in the 3D view to pick the first point of the rectangle, drag your mouse then click again to select the second point, which corresponds to the opposite corner of the rectangle. When clicking, loosely center the rectangle on the red and green axes.
 * 6) We will now center the rectangle on the origin. I have found by experience that it is almost always a good idea to center your geometry to the axes. Click on two opposite vertices (corner points) of the rectangle, for example the upper left point and the lower right point; thirdly click on the origin point (the point at the center of the green and red axes). With the three points selected (they now should be green), click on the Constraint_Symmetric.png Constraint Symmetric icon.