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As part of a larger project, i'm trying to print a translucent green dome. I set it up as follows:

  • In Blender, create an icosphere of the maximum allowed complexity. Cut it in half and throw away one of the hemispheres.
  • Duplicate the hemisphere. Move the second one down slightly and use Subtract, to hollow it out. Clean up the vertex garbage left behind.
  • Export the model. Import it in the slicer, scale to the proper size, and export as gcode.
  • Print the model with translucent green filament at 100% solid infill.

I ended up with a beautifully rounded dome that doesn't feel at all like a polyhedron, so that worked out fine. The only problem is, it's solid green. The filament seems to lose its translucency past a certain thickness, and the fact that my "solid" print is actually made up of thousands of tiny strings pressed up against each other probably doesn't help.

I tried reprinting it in Spiral Vase mode, and while the print turned out to be transparent, it was also extremely thin and fragile, and it failed anyway because of lack of support once the dome's angle got bad enough.

I've been trying to think of how to print this properly, but nothing I think of will work:

  • Scaling can make the walls thinner, but only by reducing the size of the model. Its basic dimensions need to remain unchanged.
  • Doing the same trick again that I used to create the dome, subtracting a copy of itself moved down slightly, would lead to non-uniform thickness in the model. (Which I already have some of. But when the thickness is directly correlated to the degree of transparency, this is problematic.)

Does anyone know of any tricks I can use to get it to come out properly? For reference, I'm using Blender as my 3D software, IdeaMaker as my slicer, and printing on a Raise3D N2 Plus printer.

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    $\begingroup$ You use the terms transparent and translucent interchangeably. I realize that's semantics, but translucent is semi-clear, while transparent is clear (like glass). $\endgroup$
    – Pᴀᴜʟsᴛᴇʀ2
    Feb 10 '19 at 22:46
  • $\begingroup$ Why can't you duplicate and reduce the entire icosphere, and then use "Boolean Intersection" (at least, that's the command name in MeshMixer) to hollow out the larger sphere? $\endgroup$
    – Carl Witthoft
    Feb 11 '19 at 18:57
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The filament seems to lose its translucency past a certain thickness

That's exactly the point. Think of translucency as a percentage of light being allowed through, per amount of material. 2x the material means 1/2 the light. You need either less material (which becomes brittle as you saw), or a more translucent material. I think it has little to do with the model itself.

Also - check out OnShape. One of the features it has is a "shell" function, that does what you're describing - takes a single 3D feature and creates a shell out of it of consistent thickness.

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  • $\begingroup$ OnShape looks interesting... right up until I hit the registration wall. Having to sign up for a "service" that, in all honesty, I'm likely to use once ever, instead of them simply offering a download like any civilized software developer would do, is a bit offputting. $\endgroup$
    – Mason Wheeler
    Feb 11 '19 at 10:50
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    $\begingroup$ fwiw - there's a perpetual free tier that forces your stuff public. similar to the github model. i have no relationship with them, just find the software useful and approachable. $\endgroup$
    – kolosy
    Feb 11 '19 at 15:47
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For the modeling, I suggest to change to a proper CAD software, design a half sidecut and create the model by rotating it around Z. That way you'd create an evenly thick part.

As for loosing transparency, that has several reasons:

  • light loss into printed materials is mainly due to air being captured in the model. To get the air out as much as possible and generate an almost entirely transparent print, I have printed some lens-tests with extra heat and deliberately overextruding to fill all the cavities and voids.
  • light loss in materials is also dependant on the material factor and thickness.

If you go away from FDM and look into resin-based SLA/DLP systems, you can get almost fully transparent prints with very low colored resins.

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