Reagent rack covers for QuidelOrtho Vision analysers

A set of covers that can be placed over QuidelOrtho Vision/Vision Swift reagent racks that contain bottles fitted with evaporation caps, to further limit evaporation when in storage, so there is no need to keep swapping between evaporation caps and original caps when moving to and from the analyser. The rear arm on each rack also allows the lid to be hung as an indicator of what's loaded on an analyser, using my other project (Surgiscreen antigram holder for QuidelOrtho Vision analysers).

Please note that I strongly recommend that these are printed in ASA, for the following two reasons (both because of ASA's solubility in acetone):

• The arms will need gluing to the covers after printing, to ensure they remain stable on the racks. If using ASA then this can be done easily with acetone, which when painted onto the attachment points will dissolve the ASA long enough to form a permanent bond when pressed together.

• These reagent rack covers will be in close proximity to biological reagents, so should be post-processed after printing to ensure nothing can soak in the cracks between extrusion lines. This can be easily done by allowing each rack to sit in a vapour chamber filled with acetone, which will gently melt the surface filament and fuse all of the gaps (method described below).

For each cover that you want, print one lid and one arm (You can add instances of the arms to the last platter and print as many as you need in one go, but the lids are best done individually to prevent warping ruining a print run). Post-process the lid to seal it, and glue one arm in the position shown in the image below, so the arm lies on the same plane as the base of the lid. There are two different heights of lid - short for 11-bottle racks, and tall for 6-bottle racks. The 3MF file has 7 lids with text preconfigured for racks that I needed, but the text on each is directly editable if you need different ones, and you should be able to see the expected text output on the underside of the object in the preview window of the platter tab. The extruders are set up as (1) neutral/beige for the main body, (2) black for most text, and (3) red for text relating to enzyme-treated cells - These can also be changed if necessary. If you don't have access to multimaterial printing, you can right click the text modifier, select "Change type" and change it to "Negative volume" to render the text as engraved into the lid instead.

Vapour chamber setup

A simple way to set up a vapour chamber is to place the printed cover on woven or perforated metal mesh bent on the edges to make it a slightly raised platform (place the part lettering up, as the mesh will leave a slight imprint on the bottom of whatever rests on it), such that both will fit comfortable inside a sealable polypropylene food container.

Ensure this is done in a well-ventilated area like an open garage to avoid persisting fumes. Before placing anything in the container, acetone should fill the container to a level somewhere below the top of the raised mesh platform. The platform is then placed in, and the plastic part placed on the platform afterwards. A strip of absorbent material like kitchen roll can be placed inside to increase the evaporation surface area up the walls, as long as it is not allowed to make contact with the plastic part which will damage its surface. The lid should then be sealed on three corners only, which will prevent the majority of the acetone vapour from escaping without building up pressure inside the container. After about 30 minutes, carefully remove the lid (to avoid splashing acetone around), remove the platform (avoiding touching the wet plastic as this will leave fingerprint blemishes), and allow the acetone on the surface to evaporate for 5 to 10 minutes. Layer lines may appear evident while wet, but these should smooth out somewhat as it dries. The remaining acetone in the chamber should be relatively free from plastic contamination, so it can be poured back into the original container for future vapour chamber use (though I would not recommend using it for other purposes that call for pure uncontaminated acetone).