Cylinder Seals

From the Metropolitan Museum of Art:

In ancient Mesopotamia, a cylinder-shaped seal could be rolled on a variety of objects made of clay. When seals were impressed on tablets or tablet cases the seal impressions served to identify the authority responsible for what was written in the documents, much as a signature does today. When seals were impressed on sealings — lumps of clay that were used to secure doors and the lids of storage jars— the seal impressions served to identify their owner and protect against unauthorized opening. Many cylinder seals have survived because they were made of durable materials, particularly stone, but also metal and fired clay. Perforated through the middle like a bead, seals were also believed to have apotropaic, or protective, functions and were worn as jewelry or pinned on garments.

 

Sacred and secular ideas, fundamental to the beliefs of ancient Mesopotamian peoples, were visualized in the miniature images carved on the seals. The carver used intaglio, a technique in which the forms were cut into the stone, to create the raised impression. The challenge of the seal carver was to create a design that would maintain its balance and clarity when rolled out only half its length on a small surface or twice its length on a larger surface. On the left and right edges of the impression one can see how the rolled out design begins to repeat. Unlike much of the art of the ancient Near East, which survives only in a fragmentary state, cylinder seals are in the unique position of appearing almost exactly as they would have looked to the ancient people who used them.

Objective

Have students look at several examples of cylinder seals. Challenge student to recreate ancient seals or create a modern day version. If creating a modern day version, encourage students to create icons of ideas that represent themselves. For instance, I am a teacher who lives in Brooklyn who works with 3D printing:

Remember to reverse your icons

Additional Resources:

• http://3dp.rocks/lithophane/
• Photoshop
• Inkscape
• Clay

Lesson:

If you want to use an image from the Met:

Determine the perimeter of the cylinder you would like to work with. The formula to find the perimeter of the circle with a given diameter is π D.

1. Navigate to the Met’s collection.
2. Search “Cylinder Seal”.
3. Select an image and download it.
4. Open the image in Photoshop.
5. Increase the contrast by opening up Levels and adjusting the handles (Command L).
6. Save the file.
7. Navigate to the website http://3dp.rocks/lithophane/.
8. Under Settings select Model and set maximum size to 50.
9. Click on Image tab and upload your image.
10. Click on Model tab and select Solid Cylinder.
11. Click Refresh.
12. Download the new STL file.
13. Open Tinkercad.
14. Import the cylinder.
15. Take a pair of calipers and measure the diameter of a pencil or dowel. Make a note of the dimension.
16. Create a cylinder with a diameter 0.4mm more than the diameter you just measured.
17. Align the seal and new cylinder.
18. Convert the new cylinder to a hole.
19. Group the objects to remove the newer cylinder.
20. Export the seal.
21. Print.

If you want to create your own:

1. Open Photoshop and create a black background. Use white to draw your symbol. This one represents a modern signature for myself:

   

2. Save the image as a png.
3. Open Inkscape and import the png:

   

   

4. Trace the bitmap:

   

5. Enable Live Preview:

   

6. Click OK and close Trace bitmap dialog:

   

7. Move the traced image to the upper left and delete the original bitmap:

   

8. Scale the image:

   

9. Open Document Properties:

   

10. Resize Page to Content:

    

11. Resize Page to drawing:

    

12. Save as an SVG:

    

13. Open Fusion 360 and create a sketch:

    

14. Select the XY plane:

    

15. Create a circle with the diameter of the width of our SVG minus 5 and divide that expression by Pi:

    

16. Draw a vertical line:

    

17. Offset the line by .5mm:

    

18. Trim (type T):

    

19. Convert the vertical lines to construction lines:

    

    

20. Stop sketch and open Sheet Metal:

    

21. Select Flange:

    

22. Click on the circle and set the height to the height of your SVG plus 1mm:

    

23. Extrude the edge by 0.5mm:

    

24. Select Modify->Unfold:

    

25. Click OK:

    

26. Create a sketch on the back side. Insert an SVG:

    

    

    

27. Align the SVG. Add a rectangle if necessary:

    

28. Select Refold:

    

29. Inspect the seal to look for model issues:

    

30. Back in Solid mode create a sketch on the top of the seal:

    

31. Add the center circle. Measure your dowel, pen, or pencil and add .4mm:

    

    

32. Add a second circle:

    

33. Add a third circle:

    

34. Add vertical lines:

    

35. Trim outer circle:

    

36. Extrude the center (make sure to Join the extrusion):

    

37. Export and print.

Project Objectives

• Produce a digital model
• Prepare a model for 3D printing
• Mixing digital fabrication with traditional crafts

Recommended age range 10+
Category: Beginner lessons+
Tags: 3D CAD, 3D printing, 3D printed, beginners, design, art, museum, education
Software: Photoshop, Inkscape, Fusion 360, or Photoshop, Image to Lithophane, and Tinkercad
Lesson Duration: If designing original seals, provide two 45-minute class periods for developing Photoshop, Inkscape, and model files. If using imagery from museum, provide one class period to prepare seal. (Consider additional time to print designs.)