3D Printed Lithophane in Foam Jack O' Lantern

I upped my personalized foam pumpkins last year by integrating 3D printed lithophanes, but ran out of foam pumpkins. I've improved the process this year by eliminated the sharp edges/corners, and bought more foam pumpkins.

• Craft foam pumpkin. Hollow, not solid. I've been using the Ashley brand from Michaels. They often have 25 to 30% off coupons, and go on sale for 60% off before October.
• LED tea light, or the LED linked below.
• https://www.amazon.com/gp/product/B07W726LD5
• 3D printer
• PLA Filament. There is an eSun white that is typically recommended for lithophanes, but for this style I suggest an office white that matches better with the shade of the carved foam pumpkin.
• Hot glue gun
• Orange hot glue (or optionally clear)
• Color 2D printer (color laser is what I used)
• Double sided clear tape
• Exacto Knife
• Pumpkin carving tools (specifically a scraper)
• Carbon Paper
• Pencil
• Software:
• Slicer (Cura for instance)
• ItsLitho.com (for create the lithophanes. They have an option for color lithophanes).
• TinkerCAD.com
• Blender.org (free 3D program)
• Lunapic.com

This step can be skipped, but I highly recommend it, it creates a nicer result. Open Lunapic.com in your web browser. Upload the image you want to use. Use the remove background option, and click a spot of the background. Doesn't get over zealous with the percentage, or you may remove some of the foreground. Bit by by, detect and remove sections of the brackground. There is also an eraser tool, so you can do some manually. Zoom in to the image where necessary, and try to smooth out the foreground image as well as you can.  

Note: While the lithophane application will allow you to tweak the brightness and contrast settings, it will affect the background; so you may want to return to LunaPic and make those adjustments there before saving.

Export/save the image as a PNG (to maintain the transparent background). Rename the file (now in your download folder) to something more helpful, like the family's name.

Open ItsLitho.com in your web browser.

Select create.

On the image tab, upload the image.

If you removed the background (make it transparent), set the option for Bg intensity - Set to zero (so background is solid black, no/less light coming through).

You could optionally adjust the brightness and contrast here, but if you made the background transparent those settings will affect it as well.

On the "EDIT" tab, change the shape to "Arc".

Change the "angle" to either 30 (for small width images) or 45 (for larger width images). This will follow the curves of the foam pumpkin better.

Set "Frame" to "none".

Set "Height" to "100mm".

The application will fill in the width for you.

Leave "Min Thick" as "0.8mm".

Change "Max Thick" from "3.2mm to "2.00mm".

Save/Generate the Lithophane. Here you will see an option for the color lithophane, save that as well. You'll have an STL and a PNG file saved in your download folder.

Using TinkerCAD create an oval shape. Create a rectangle as well.

Position the oval into the center of the rectangle, and make it hollow.

Combine the two objects.

Save it as an STL. Or just download the one I provided.

Note: This took me longer to figure out than I care to admit. TinkerCAD has a maxium file size limit. MeshMixer failed to produce the result I wanted.

Open the 3D modeling tool Blender. Import the lithophane STL. Also import the Arch STL.

Rotate the Arch so it is oriented the same as the lithophane.

Now adjust the height, width, and depth of the Arch to cover the corners and edges of the lithophane.

You'll want your image positied/visible in the Arch/oval; the rest of the shape is goind to be removed.

Select the Lithophane

Click the "Wrench" icon.

Apply modified / Add Modifier

Select "Boolean"

Select "Difference"

For "Object:" Select the Oval/Arch object.

Select "APPLY!" (this step may take a little time)

Delete the Arch

Export the modified lithophane object to a new STL "FamilyName-Oval.stl"

The STL must be converted to GCode for printing. I use Cura for my slicer. Adjust the settings to optimize the quality of the Lithophane.

Print upright. Slow the print speed down. Enable brim, to help hold the lithophane upright while printing.

Because it's now an Oval lithophane (and not a rectangle) its going to need some supports to keep the print from failing; but DO NOT use auto generated supports (otherwise they will attach to the image, and reduce the print quality. Install (if not already present) "Cylindrical Supports". This will let you place custom supports only where you want them. Place two or four as pictured, along the bottom edge of the Oval. This, along with the brim, will help support the lithophane while printing.

Load the off-white (Ivory) filament into the printer.

Load the generated Gcode into your printer, and wait for printing to complete.

Optionally, using a 2D printer (Color Laser if you have it), print the PNG created by ItsLitho.

Also (optionally) use Word Processor to create a 45 or 60 font sized text of a phase of the family name, for 2D printing.

Last year I did a few that said "Thankful", this year I used last names.

Trim the color lithophane, and use clear double sided tape to attach to the back of the 3D printed lithophane (unless you prefer the B&W look. I think the color one looks better.).

Tape the phrase or name to foam pumpkin, and use carbon paper to trace the outline of the text onto the foam pumpkin.

Use the scraper tool to remove the orange flesh from the pumpkin for the traced letters. The deeper you scrape, the more light will shine through when illuminated.

Align the lithophane under the text, and trace around the oval.

Using the exacto knife cut the traced oval out.

Place the 3D lithophane into the cut out shape. Hot glue around the edge to hold the lithophane in place.

Cut a hole in the lower back for the tea light or other light source.

Install the light, and hot glue in place.

Admire your handy work, and gift it to the appropriate friend or family member.