In the Invention Studio, we go through a LOT of filament for our printers, and we always seem to have a ton of filament spools laying around. Usually we throw them out, but I always feel bad about it - especially since we're always in need of small storage.

I got an idea to upcycle a few of them into a desktop compartmentalized storage unit. The spools spin freely around a center access, providing convenient access to each of the compartments. With just a few household items, you can also upcycle your old filament spools into small storage!

Step 1: BOM

So, to make these cabinets, I gathered the following materials:

Safety:

Respirator

Ventilated area

Materials:

Paper towel tube

Cardboard box

Empty filament spools

Spray paint

Tools:

Hot glue gun

Utility knife

Scissors

Ruler

Permanent Marker

Step 2: Peel Off Stickers. (optional)

I wanted these to look as nice as possible, so I quickly peeled off the stickers.

Step 3: Take Measurements and Do Math!

To make these cabinets, we'll be making 4 doors per spool. Each door will have a wall attached to it, to keep the compartments separate. To get snug fitting doors, we'll have to do some quick math!

Get the following measurements:
1. Big diameter, D = 7-7/8"
2. Little diameter, d = 4-1/2"
3. Height, h = 1-3/4"
Calculate the length of the wall, which runs from the inner diameter, to the outer diameter.
1. delta = (D-d)/2 = 1.6875"
Calculate the outer circumference of the spool.
1. c = 2*pi*r = pi*D = 24.7"
Calculate the length of the cabinet door, assuming 4 doors
1. l = c/4 = 6.175"
Calculate the total length of the cut required to make both the door and the wall.
1. l+delta = 8.8625"

Step 4: Draw Out Your Cabinet Cutouts.

On a piece of cardboard, draw rectangles with the shown dimensions. Because we will be taking advantage of the corrugation to help us bend our cabinet doors, you'll want to make sure that the length is perpendicular to the corrugation of the cardboard.

Step 5: Cut Out Enough Rectangles for Your Doors.

Using a straight edge and your utility knife, cut out enough doors for your assembly. Because I'm doing 3 filament spools with 4 doors each, I needed 12 total rectangles. Make sure you leave the wall and door parts attached.

It's also a good idea to test the fit of your doors in your spools as you're going. The doors will end up being press fit into the spools, and so a tight fit is desired.

Step 6: Bend and Secure All of the Walls.

Bend all of the doors at the delta line to a 90 degree angle. Secure those walls with a bead of hot glue.

Step 7: Bend the Doors to Match the Spool Curvature.

Using the corrugation, bend the doors to match the curvature of the outer edge of the spool. Run beads of hot glue along the inside of the bends to keep the doors in that shape. Repeat for all doors.

Step 8: Draw and Cut Out the Spacers.

You need cardboard spacers so that the cabinets can rotate independently. The inner diameter of the spacers need to roughly match the outside of the paper towel tube, and the outer diameters of the spacers need to be larger than the inner diameter of the filament spools.

For this cabinet, you need 3 spacers, and 1 top. The top doesn't have the center cut out of it.

Step 9: Cut and Glue Little Handles for the Doors.

The size of these doesn't really matter, it's just whatever is comfortable for you. Glue these close to the side of the door opposite from the wall.

Step 10: Paint Everything.

Step 11: Attach the Top to the Top of Your Paper Towel Roll.

Hot glue is your friend.

Step 12: Glue Doors Into the Spools.

Hot glue is still your friend.

Put a bead of hot glue along all 3 free sides of the wall of each door, and slide it into position in the spool. Wait for the bead to cool before adding more doors.

Step 13: Assemble the Doors.

Slide a spool up the bottom of the paper towel roll, then slide a spacer up the bottom of the roll. Use hot glue to secure the spacer in place on the paper towel roll, to allow for smooth rotation of the spool. Make sure you add enough space to allow the spool beneath to rotate freely. Then, repeat the process for the other 2 spools.

When you get to the last spacer, trim off the excess paper towel tube before you glue on the last spacer.

And... you're done! Enjoy!