DIY Labware: the advanced cupholder

  • Posted on 5 January, 2017
by David McClymont

Sometimes your liquid handling robot needs to be able to use tubes but they have to be placed in exactly the correct position every time. 3D printing is something most people are aware of, but for me the stumbling block was always the 3D modelling in software. It seemed like I needed some help to get over that hump and I got that help at the Imperial College Advanced Hackspace course on Autodesk Fusion 360. The highly experienced teachers introduced us to solid modelling, surfaces and t-splines. What is particularly great about a small course is being able to ask direct questions and getting familiar with a subject that can be hard to initially do with online resources together with direct relevance to the types of 3d modelling problems I want to solve.

While Fusion 360 can do all sorts of things useful to mechanical engineers, I essentially just wanted to make a cup holder. Every so often there comes a use case where you have to aliquot some supplied liquid where it makes sense to have the 1.5 ml Eppendorf tubes on your robot deck. What most liquid handling providers offer is some CNC milled holder for tubes that creates a base the same size as a microplate, but into which you can place tubes in holes positioning them in such a way the robot knows exactly where to aspirate from. These can be surprisingly expensive but are simple to model as all the dimensions are based on the ANSI/SLAS standard (

After just one lesson I had enough skills to model an Eppendorf tube holder using Fusion 360, the technical drawings for a 48 well plate and the technical drawing for an Eppendorf tube. I decided to cut out most of the model and only create enough space for 8 tubes as more plastic just means much more time on the 3d printer. The imperial college advance hackspace offers a number of ultimaker 3d printers which an open resource based on donations for plastic use. As I watched the model appear I was surprisingly proud to see something useful that had never existed appear before my very eyes.