I've got a bracelet concept that I've sketched up as a flat design. I'm trying to found a route by which I can extrude this into a 3d object (depth map?), curve it into a bracelet, then ultimately create a STL file out of it. I'm having trouble finding a way to do this that allows me to "warp" the flat object into a bracelet before I try to print.

Is there a recommend technique for this? I'm not worried about representation of the picture; it's effectively meant to be an 'etched' pattern.

  • $\begingroup$ Welcome to 3D Printing! $\endgroup$ – Pᴀᴜʟsᴛᴇʀ2 Sep 6 '18 at 22:53

Easy peasy. Go to 3dp.rocks and select the output shape you desire. I've had excellent results making flat lithopanes. I created a couple curved STLs which look fine in Cura; just didn't print them.

  • $\begingroup$ I have had a lot of success using this $\endgroup$ – EvilTeach Sep 9 '18 at 16:09

This may not be your cuppa tea, but if you're willing to learn to use OpenSCAD or already know how, there's a Thingiverse post that appears to directly address your objective.

Correction, this particular post on Thingiverse consists of a series of Python files, of which I have zero experience/qualifications. It may still be of value, if you are Python capable.

santa on a mug

Another resource that is strictly OpenSCAD is from Eric Buijs, a rather talented 3D design person. His YouTube channel has a number of useful tutorials for both OpenSCAD and Solvespace. This video in particular describes applying a flat object to a curved one using OpenSCAD, resulting in a lithophane.

curved lithophane

As I created this answer, I did not re-watch the 12+ minute video, but I recall how he explains clearly how the program dissects the surface into a number of flat panels and then superimposes the image on each segment. From this presentation, I suspect one could expand to a full cylinder.


This is the best and simplest way I've found to transform a flat design into a 3D object that you can then save as an STL file: Blender-Converting 2D Image to 3D Object

This solution requires you to use Blender and Inkscape, both softwares are open-source and available for free at this time.

As suggested below by @Greenonline, I will provide a step by step in case the video is removed from Youtube. I'm sorry that I cannot provide screenshots at the moment, but I'm on a trip and writing from an old laptop that cannot run either Blender or Inkscape.

  1. Load your image in Inkscape.

    • Format is unimportant as long as Inkscape can read it. It works with black and white and color images, but please note that color information won't be sent to Blender in the end, you'll have to add color materials yourself once the picture has been converted to a 3D object.
  2. Select the image or the portion of it that you want to turn into a 3D object.

    • For some unknown reason, Inkscape doesn't automatically select the image you loaded into it, so you have to do it manually. When the image is selected, it will be surrounded by a dotted line and you'll see arrows appear on the sides and corners.
  3. Go to Path > Trace Bitmap, or use Shift+Alt+B, and a pop-up window will appear. Keep the default settings, just make sure that the 'Remove background' option, located at the bottom of the window, is checked, then click OK.

    • You can see the result of the operation in the 'Preview' window. If the 'Preview' is empty, just click on the 'Update' button located below 'Preview'. If it is still empty after you clicked on 'Update', then you haven't selected your picture as indicated in Step 2!
  4. Got to File > Save As and save your file as 'Plain svg'.

    • Saving as 'Inkscape svg' should work as well, but it's always best to use the standard format.

And you're done with Inkscape, time to switch to Blender.

  1. Go to File > Import > Scalable Vector Graphics (.svg) and import the picture you just created in Inkscape.

    • If you do not see Scalable Vector Graphics (.svg) in the list of importable files, it means the add-on hasn't been activated. You can do it by going to File > User Preferences > Add-ons then typing 'svg' in the search field will bring up the relevant add-on (Import-Export: Scalable Vector Graphics (SVG) format). Clicking the checkbox next to it's name will automatically activate it.
    • The picture will usually appear very small in Blender. Press 5 on the numeric keyboard to home onto it, then you can stretch it to the desired size by using the relevant tools in Blender.
    • It might be a good idea to move the object center into the middle of the geometry, although, from personal experience, you can do it after it becomes 3D without too much trouble.
  2. Your picture has been loaded in Blender as a Curve object. Go to the 'Curve' tab and in the 'Geometry' sub-menu you can use the 'Extrude' slider to give depth to your picture.

  3. Finally, once you've extruded your curve to your satisfaction, go to Object > Convert To > Mesh from Curve/Meta/Surf/Text, or use Alt+C, and voila, you're done!

You know have a nice 3D object made of polygons that you can modify at your leisure using Blender's tools.

  • $\begingroup$ Could you edit your answer to include details (or at least the main points, actions, menu items) from the video, because if the video is ever removed then your answer will not be as useful as it could be. $\endgroup$ – Greenonline Sep 12 '18 at 6:03

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