His trade had taught him delicate motor skills, and he soon produced quality mounts that overshadowed those of other preparers.
Until the early 1780s, slide-making was simply a hobby for Ypelaar.
Some of his larger sets included elongated ebony or brass holders for the circular preparations, facilitating easy viewing on any microscope stage. The set is accompanied by a handwritten list of the specimens, stamped with "A Ypelaar" (see Figure 6).
Ypelaar’s use of glass covers, rather than mica, can help discriminate between those preparations that were and were not made by him.
The thickness of the glasses range between 0.2 and 0.7 mm, with a slight curve indicative of production from glass blown into a large, thin bulb.
He trained to be a diamond cutter and setter, and later became a master of the craft and a diamond merchant. Both of his parents had died by the time he married Anna van Dijk in 1762 As a youth, Ypelaar developed strong interests in nature and biology.
Inspired by the writings of microscopists such as Leeuwenhoek and Swammerdam, Ypelaar sought to replicate their observations.