pencil holder which can be hung on the inside of a school locker (or stood up on a desk). This was an idea my 8th grade son had - something he needed - so I took on this not-so-challenging challenge. This post tells a bit more about how it was made.
I wanted to avoid making it a simple hollowed out half cylinder (flat side to hang on the locker or wall), so I designed it from scratch. First, I drew the bottom shape - a rectangle, basically, 30mm deep and 70mm wide, with clipped front corners to give it a bit of design.
Then I extruded that as a solid - 100 mm high - and then used the "Shell" command in Autodesk 123D Design - which hollows out any shape. I'm finding that feature to be most useful - you select the face of the object you want to "shell" and then adjust the width of the remaining walls. I made the walls 3mm thick.
Then I adjusted the back to be 4mm (by "pull"ing the back face) so that I would have additional area for an indent in the back to hold magnetic strips. That indent is 1mm deep. and about 30mm wide x 50mm high. It is also beveled at the top to avoid any overhangs which might not print nicely. I also put a diamond shaped hole at the back in case this cup needed to hang on a nail or hook (I think of everything, 12% of the time).
The shape was still too boring. So I began making a grid of shapes that I would "subtract" from the face and sides, to make it more like a mesh. I took a simple small square, turned it 45 degrees to make it look like a diamond, then duplicated it a bunch of times. I positioned all the squared equal distance from each other and lined them up to be on the same plane. I then sunk them into the face of the cup so they were sticking out the front and through the back of that front wall - the "Subtract"ed them (that is a command in 123D which is by far the most useful thing in my projects so far). That left the diamond pattern you see on the front face. I then repeated a similar, but slightly different set of diamonds for the bevels and the side walls of the cup.
The print was by far the longest so far - 8 hours and 38 minutes. I took a risk and let this print overnight - and by the morning, there it stood. My pencil cup (well, my son's pencil cup). Something that I could have bought at Staples for a few bucks. But then, it wouldn't have been mine (well, my son's), and I wouldn't have learned a darn thing. That said, Staples has nothing to worry about ;)
Model: Pencil Cup
Modeling App: Autodesk 123D
Slicing App: Slic3r
Filament: LulzBot PLA 3mm Green
Print Time: 8 Hrs. 38 Min.