Microslides are commonly used to store microfossils such as foraminifera. The standard dimensions are 76 mm in length, 26 mm in width and 2 mm in depth. There are other dimensions but they will not fit into standard slabs or cases.
The material is either plastic in total or a cardboard base, an aluminum holder and a glass coverslide.
The microslides may have one or up to 4 holes to loosely store specimens. So called plummer cells have a grit with up to 64 single fields, where specimens need to be fixed.

Commonly cardboard slides are used as they are almost antistatic in contrast to the plastic cells. Cardboard slides need to be well manufactured not leaving small clefts. Clefts between cardboard-layers at the bottom may cause small specimens below 200µm to vanish. Clefts between cardboard and glass may cause their loss. Among others Kreativika provides very well manufactured cardboard-slides.
The problem with the plastic cells is that they generate static electricity though sometimes being described as antistatic. Specimens may jump off or cling to the cover. When opening the cell the clinged specimens are easily damaged or destroyed. Aspirating into the plastic cell or impregnating will help a little against static. Plastic cells are about 30% cheaper. They are available with one hole only.

As many foraminifera are whitish and/or transparent a black cell provides the best perceptibility. For darker coloured foraminifera such as some agglutinates white cells may be better.

To store a collection of sorted specimens plummer cells may be used. The specimens need to be fixed in single fields. A low concentrated water-sugar-solution or water-solutable glue should be used to be able to turn the specimens later. As they cannot be moved when observed two or more of a kind should be placed in a single field with different orientation. To fill a plummercell as the one to the left with specimens from Antarctica requires a lot of time, dedication and a steady hand for precise positioning.

Each cell should be labelled at once. After many years paper-labels may be destroyed by light, paper-eating creatures or bad luck. Numbering with something durable may be an option, but the list to explain the content needs to be always connected to the collection. We know of unfortunate collections where the list is lost.
Slabs are useful to see at once what is in it. Cells may collect dust if the slab is kept open. Slabs may be easily piled and stored in any cupboard. Storing cells in different boxes just at hand may result in a messy collection.