Prepare an epidermal impression by coating the leaf surface with nail varnish. Peel off the dried layer of nail varnish by using sellotape and stick this onto a slide.

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https://www.saps.org.uk/secondary/teaching-resources/299-measuring-stomatal-density#:~:text=Prepare%20an%20epidermal%20impression%20by,and%20place%20under%20the%20microscope

Clear plastic sheets of various materials and thicknesses were obtained and cut into rectangular pieces equivalent to the size of large commercially available microscope slides (75 × 150 mm). Leaf epidermal impressions were made directly onto 50 × 75 mm slides fashioned from 0.16 mm (1/16 in) cellulose acetate (CA), 4.74 mm (3/16 in) cellulose acetate butyrate (CAB), 2.03 mm (5/64 in) polymethyl methacrylate (PMMA), or 3.17 (1/8 in) clear polished polyvinylchloride (PVC). Solvents (acetone or MeCl2 for CA and CAB, and methylene chloride or methylethylketone for the PMMA and PVC) were applied directly onto a fresh leaf that was sandwiched between two pieces of 4.74 mm (1/16 in) aluminum plate one of which was faced with closed cell Neoprene foam in contact with the leaf. Th e resulting sandwich was held in place for about 5 min with spring steel clips. Th e foam was removed and the leaf subsequently peeled from the slide revealing the epidermal impression. We also investigated using a clear gloss spray laquer (Deft Inc., Irvine CA, www.deft fi nishes.com). Leaves were simply taken to the fume hood, both surfaces coated with spray laquer, allowed to dry, given a second coat, allowed to dry, the replicas lift ed from the leaf surface with clear urethane packing tape and placed on a plastic 50 × 75 mm slide for viewing. Th e resulting epidermal impressions were viewed by bright fi eld microscopy with an Olympus BX60 compound microscope (Olympus Optical Co., Tokyo, Japan).1 Images were captured with a RT Spot Color digital camera and Spot version 3.5 imaging soft ware (Diagnostic Images Inc., Sterling Heights, MI).

If you can prepare epidermal strips, you can directly visualize them under a light microscope after staining with 1 % saffranin.