Pin the Menubar: Upper left of the screen, Solidworks logo, hover on the black triangle to the right of the logo to expand the menu. On the right end of that menu bar, there is a grey pushpin. Click it to pin the Menubar open.

Start a New Part: File, New…, Part.

Units: Tools, Options…, Document Properties, Units, IPS (inch, pound, second)

View Selector: View, Toolbars, Standard Views  [the plane with the arrow sticking up is the Normal To view.]

Hierarchy in the Left Column: Click on the Front Plane to select it. Click on Normal To to lay it flat on the screen.

Insert, Sketch, click on the blue border of the Front Plane to place the sketch on that plane. Red coordinate origin appears. Note on the upper right of the main window the two icons. The red X exits the sketch without saving your work. The pencil with the swoopy arrow saves your work and then exits.

Draw a Line: Tools, Sketch Entities, Line. Click, release, and then drag to draw a line in any direction. In the Hierarchy on the left, you can choose to make the line Horizontal or Vertical. You will remain in the Draw Line tool until you double click at the end of a line, or until you hit Esc.

Draw a Rectangle: Draw 3 more lines, snapping them to the endpoints of the previous lines to make a rectangle. (Or a 4 sided irregular polygon if you don’t make the lines horizontal (top and bottom lines) and vertical (right and left lines).

Draw a Centerline snapped to the midpoint of the left and right vertical lines: Tools, Sketch Entities, Centerline. Hover over the left vertical line, near the midpoint of the line. The cursor indicator will show yellow, with a green square in the middle of a black line in the icon. Click there, and then drag to snap to the midpoint of the right side vertical line using the same clues. Double-click or hit Esc to stop making lines.

Center the Rectangle on the Origin: Tools, Relations, Add. Click on the origin to add it to the list in the left panel. Then click on the centerline. On the left you will see two choices, Midpoint and Coincident. Choose Midpoint. Click the green checkmark on the upper left to accept that relation.

Now your rectangle is centered on the Origin. This is important for future operations. Always make the object symmetric about the origin, if it has symmetry.

Set the Physical Size of the Rectangle: Tools, Dimensions, Smart. Click on the vertical line, release, pull away some distance to locate the dimension value, and click to set the location. A Modify panel opens, in which you can type the dimension you want. Click the green check in the upper left when you are happy with your dimensions. If you want to change a dimension, click on the dimension text to reopen the Modify panel.

When your sketch is fully dimensioned, the geometry will turn from blue to black. It’s very important to make sure your sketches are fully dimensioned, so you can’t accidentally drag part of the sketch out of shape. Use dimensions or relations to other parts of the geometry. Never use the Fix relation if you can possibly avoid it.

Unsolvable: If your geometry turns yellow or red and you get a warning “Unsolvable”, that means you have made conflicting relations. Go to Tools, Relations, Display/ Delete Relations, and delete some until the geometry goes blue or black. If it is blue, then add new relations, or dimensions, until it is fully defined = black.

When you are happy with your sketch, click on the swoopy arrow on the upper right to exit and save the sketch.

Save your file: File, Save.

Give your file a meaningful name if you can, so that the you a month from now will be happy with the you now. Don’t call it “block” or “pin”, because you are going to make lots of things like that. If no particular name occurs to you, use a date string that will at least sort it properly in an alphabetic list. 20161106a.SLDPRT will show up before 20161106b.SLDPRT, and so on. 

Make the Part 3 Dimensional: Click on Sketch1 in the hierarchy on the left. Tools, Insert, Boss/Base, Extrude. In the Boss-Extrude panel on the left, enter a value for the dimension of the extrusion. From the pulldown menu where it shows Blind (a one direction extrusion), choose Mid-Plane to make the part symmetric around the origin. Always make your parts symmetric around the origin unless you have a compelling reason not to. Click the green check mark on the upper left to accept the extrusion.

Experiment with adding more Extruded Boss/Base material to the part, and with removing material using an Extruded Cut.

Elephant Toy — Rough Draft

rough-draft-full-toy in SolidWorks format


I used a funny kind of rubber instead of sand because it has the same density as loose sand.

Stability: Check the center of mass as you rotate the part into all possible orientations. If center of mass is closer to the closed end of the dome bottom than the contact point with the ground is, then the toy will be self-righting.


  1. Demonstrate Finite Element Analysis of the weakest dome member if made of Balsa Wood, for which there is engineering data in SolidWorks.
  2. Run an analysis of the lifting strength of the hexagonal hole in the main plate. Try a torsion test also, to simulate leverage load on the top of the tower. If the installation at MICA has Pro, check the top as an assembly.

Things that remain to be done:

  1. Split up the layers of the bottom shell into single plywood thicknesses. It can be a much better approximation of the sphere when made of more layers. Make each layer with inside and outside geometry for inner and outer bolt circles and load surfaces.
  2. Add another bolt circle to hold the middle deck, using the stainless nut inserts.
  3. Choose screws for holding plywood layers together. I recommend these. Space them 2 to 3″ apart.
  4. Make a bill of materials. Order materials and fasteners. And router bits for the CNC router. Make sure you are using sharp bits.
  5. Choose how many facets for tower. Order metal.
  6. Must use food-grade anti-seize lubricant on the screws, because stainless to stainless contacts will gall (weld) to each other. Or switch to non-stainless fasteners, which will cost less, but will rust. Perhaps black-oxide coated stainless threaded fasteners will be good enough for anti-seize.
  7. Need chain, shackles, and chain adapter plate (made of 1/8″ steel plate, cut and bent) to attach clanger to top eye.
  8. Make a bill of materials. Order materials and fasteners. And router bits for the CNC router. Make sure you are using sharp bits.
  9. Lots and lots of fabrication work to do. Layouts, CNC router and CNC plasma cutting, glue-and-screw joining, grinding, welding. 
  10. Crochet tire hoops to be made, with manila rope or firehose or both together. Lots of work to be done here too. 


  1. Can use some of the inside cutouts of the larger base parts to make the smaller base parts. Saves some plywood.
  2. Decks should be made of 2 layers of plywood, for strength.
  3. I recommend sealing the edges with glue in 2 or 3 coats after sanding the final assembled base.
  4. Pay attention to the offsets of the welded top. I designed them specifically for thorough fusion. Weld to the main plate both inside and outside for strength.
  5. Holes at the top are for two reasons. To allow moisture to come out so the inside doesn’t rot, and to allow the insertion of a bar to hold the eye-nut still during assembly and repair of the clang chain. You may need to make a special tool for pushing the eye-nut to the end of the tower in the correct orientation. Something like a pipe with a notch in it.