Picking tray for paleontology & biology

Something that i found interesting during the Applied marine science course at University of Plymouth was the breath of interest and skills.

I was asked by someone on my course to help build a picking tray to help them with their project.

They had been diving collecting samples that contained foraminifera. They are less then 1mm in size, making them difficult to see. Various stains can be added to help them stand out, a microscope and paint brush is used to handle them, but this is still a challenge. In literature, picking trays have been mentioned, with some debate between various designs as it allows an area to spread a sample and keep the slide close, limiting travel and thus loss.

Using the design mentioned by Christopher J. Duffield and Elisabeth Alve in their paper we where able to build a version to use in cad. It was surprisingly easy and fast to build. The original plan was to have it milled from a single piece of clear  acrylic, but we soon found that university didn’t have the right bit to fit in the milling machine. This meant if we wanted it, we would have to order a bit in @~£50, plus material and milling time which was a shame. So instead we ended up 3d printing it.

The negative of doing it this way was that if we used transparent plastic, we where not able to get 100% transparency due to the layer bonding and the surface would not be smooth on the gradients resulting in foraminifera being trapped or damaged, but it meant we could just print as many as we wanted. In the end we made 2 different types, with and without the slide holder as well as change the colour and material type to suit. This resulted in 4 different colours being used, white, clear, blue and  fluorescent orange.

The results can be seen below.

Picking tray for Picking tray used in biology or paleontology.
Picking tray for Picking tray used in biology or paleontology. Two types with or without a slide tray


If you wish to make your own, then feel free to download. I’d be interested to see how to use yours or modify the original design.

Download “Picking Tray” picking-tray-v1.zip – Downloaded 270 times – 1 MB

Image courtesy of Germano Soru

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