3D Print Your Eyepiece

Do you have NeoLucida DIY prisms and aren’t sure how to mount them? In this section, we present downloadable CAD (.STL) files from which you can 3D print a working prism-mount eyepiece for a camera lucida. Our files are designed for use with commonly available desktop PLA/ABS printers, such as a Makerbot Replicator 2. If you don’t have access to such a printer, we offer some links below to service bureaus (such as Shapeways) that will print it for you. Once you have this eyepiece, it can be mounted onto a flex-arm camera mount, such as any of the commercially-available flex-arms discussed here.

If you just want to dive in, here are the .STL files for 3D printing:


If you’d like more guidance, please read on. This document is divided into the following sections:

  • Prism-Mount Eyepiece .STL Files, and Overview
  • Makerbot 3D Printing Settings
  • Assembling your Eyepiece
  • What If You Don’t Have a 3D Printer?

We’d like to add that we warmly welcome your own contributions, modifications, and alternative CAD models! Please keep us informed about your efforts at info@neolucida.com, @neolucida on Twitter, or /Neolucida on Facebook. 

Prism-Mount Eyepiece .STL Files, and Overview

Here you may download a set of free .STL (stereolithography) files from which you can 3D print your own NeoLucida eyepiece: neolucida_eyepiece_stl_files.zip (700kb zip). You can also download them from here at Thingiverse.com, where it is Thing #194294.

Hey, want it easy? You may purchase high-quality 3D-printed eyepieces directly through our Shapeways shop: Shapeways.com/shops/neolucida. We sell the pieces there without any markup.

The unit for these files is millimeters. There are four files contained in the zip:

  • neolucida_eyepiece_L.stl (Left-eyed version of the eyepiece)
  • neolucida_eyepiece_R.stl (Right-eyed version of the eyepiece)
  • neolucida_eyepiece_cap.stl (Eyepiece endcap)
  • neolucida_eyepiece_all.thing (Optional .thing file for Makerbot Makerware)

The eyepiece CAD model we present here has been specially optimized for 3D printing, and therefore looks somewhat different from the “usual” NeoLucida eyepiece. Our model has been successfully tested in PLA with a Makerbot Replicator 2 (without printed supports) and in ABS with a Stratasys Dimension 1200 (with dissolvable printed support material). The eyepiece pieces available through Shapeways are printed in high-resolution sintered nylon.

As with the usual NeoLucida eyepiece, the 3D printed eyepiece is designed to mount onto a 1/4″-20 UNC camera mount, which is widely standard for consumer cameras. To achieve this, the eyepiece features a receptacle which snugly holds a standard 1/4″-20 SAE hex nut.

The prism edge emerges from a notch cut from the leading edge of the body:

The prism is (carefully!) inserted through a triangular port at the far end of the eyepiece:

There is a small risk that the prism will fall out (it is held snugly in place, but YMMV), so to ensure that it doesn’t, the prism port is then shut with a separately printed endcap, which is glued in place.

If you are interested in modeling your own eyepiece, here are dimensions for the standard (SAE) 1/4″-20 hex nut we recommend using at the mounting point:


(Measurement F) Width Across Flats:
Nominal: 7/16″ (inches)
Recommended: 0.4375 in. (11.113 mm)
Min: 0.4280 in.
Max: 0.4380 in.

(Measurement G) Width Across Corners:
Min: 0.488 in.
Max: 0.505 in.

(Measurement H) Thickness:
Nominal: 7/32″ (inches)
Min: 0.212 in.
Max: 0.226 in.

For more design specifications and considerations for drafting your own eyepiece 3D model, please see this page. Incidentally, the NeoLucida prism is 5.0 x 5.0 x10.0mm.

Makerbot 3D Printing Settings

There are two versions of the eyepiece, for left-eyed and right-eyed use. You only need to print one eyepiece and one endcap, but the .thing file contained in the downloadable zip file contains both versions on the same build platform, when viewed in Makerware:

If you’re using a Makerbot, we recommend that the eyepiece should be printed vertically (as shown above), without supports. (Printing supports will botch the internal structure of the prism chamber and aperture.) We had good results with the print settings shown in the following image: Standard resolution in PLA, Raft enabled, Supports disabled, with an infill of 30%, 3 shells, and a layer height of 0.20mm. We recommend black PLA filament, for the best optical experience.

You should have some small files, snips, and sandpaper handy to finish your print if necessary.

Assembling your Eyepiece

Press-fit the 1/4″-20 hex nut into the mounting end of the eyepiece. Depending on the tolerance of your print, it may be pretty snug.

Next, clean your hands and find some cotton or latex gloves, because you’ll be handling the prism. Look at how carefully we inspected them for you!

Carefully insert the prism into the prism port until it drops all the way down into the view aperture. Keep in mind that the NeoLucida prism is fragile. Avoid getting fingerprints on the faces, and don’t chip the leading edge! You may need to gently prod it into place, using a Q-Tip (cotton swab) or other non-scratchy poker. When you’re done, it should look like this:

Finally, fit the endcap into the prism port. You can fix it there with a drop of glue.

When you’re done, you can mount your eyepiece on any of various camera-mount flex-arms. We provide a variety of options on this page. Below, the eyepiece is mounted on a Bogen/Manfrotto Magic Arm with Super Clamp and Quick Release Head. Voilà — a DIY NeoLucida!

What If You Don’t Have a 3D Printer?

3D printers are increasingly common in universities, design studios, and even elementary schools. If you’re at a university, check your school’s departments of design, architecture, or mechanical engineering to see if they’ll let you use theirs. Still, if you don’t have access to a 3D printer at work or at home, there are plenty of other options you can use to 3D print an eyepiece for your NeoLucida:

  • There are a wide variety of commercial service bureaus which will print 3D files, oftentimes with very quick turnaround and overnight shipping. We recommend Shapeways.com, where we have already uploaded our models; they ship internationally. Within the USA we also recommend Ponoko.com, or try visiting your local TechShop fabrication studio if you have one in your city. In the UK, we recommend 3DCreationLab.co.uk. In Europe and elsewhere, please see lists like this one for 3D printing bureaus in your country.
  • Visit your local Hackerspace! There are now thousands of hackerspaces and makerspaces all over the world, and there’s probably one closer than you think. These are informal places where friendly, nerdy people get together to make stuff, and many of them have 3D printers. A huge list and map of active hackerspaces can be found on the Hackerspace Wiki, at http://hackerspaces.org/wiki/List_of_Hacker_Spaces.

Good luck with your DIY camera lucida! Please keep us informed about your efforts at info@neolucida.com@neolucida on Twitter, or /Neolucida on Facebook.