How to hollow out your model?


Stereolithography (SLA) 3D printers create fully dense parts, sometimes when you do not require structural strength, hollow out your 3D model should be a good choice to devoid amounts of materials and time.

This post will give you a glance on how to hollow out 3D models with the help of two free tools Meshmixer and PreForm.

Getting started

Similar to what we do on PreForm, first you have to import the origin file into Meshmixer, better with stl file format.

Orient the model, so that the side closet to the build platform should be the one where the vent hole can be placed without influencing the function of the part. The function of vent hole will be discussed later, to keep the way the model will be best printed, always be careful with the location of the hole(s).

On the right side of the interface you see a list of tools, find “Edit -> Hollow” to start work. Meshmixer will automatically add a shell inside your model according to the default parameters.

After that, you see more advanced offsets you can specify in setting box, these are Offset Distance, Solid Accuracy, Mesh Density, Holes Per Hollow, Hole Radius and Hole Taper.

Offset Distance: adjust the thickness of the shell, in other words, adjust the volume of the hollowing part.

Solid Accuracy and Mesh Density values are set according to 8-bit values, which is to say that 256 is equivalent to 100%. For Solid  Accuracy, the greater the figure is, the more accurate the Meshmixer will attempt to provide the initial mode you imported. Mesh Density works similarly,  but it focuses on the inner surface.

Holes Per Hollow: how many holes you want to have on your model.

Hole Radius: the radius of the hole should be less than 3mm within the slider, but note that the value can be up to 10mm if you manually type in.

Hole Taper: determine the shape of the green cylinder.

*Generating the holes

One useful tool is that you can either automatically or manually adding the vent holes that connect the interior and outer shell, it allows the resin and air to flow while printing, so that the inner supports can be removed.

Find “Edit -> Hollow -> Generate Holes” to automatically generate set number of holes according to the settings. Or you can manually add holes by clicking left mouse on your model, drag the red sphere to reposition the hole on the surface. Double click the red sphere if you want to disregard a hole.

If you are happy with the settings, click “Accept” the model will be hollowed within a few minutes. You are ready to print.

Export your model in stl or obj format and import it to PreForm if Meshmixer cannot access to your printer. Next steps should be the same as what we do on PreForm.