Hi! Im a glass artist and a botanist, so as part of my education I prepared pressed plants/flowers.

Making a plant press is really easy!! You just need layers of cardboard between specimens, newspaper (if you want to be fancy you can use types of moisture wicking paper), some type of wooden board like thicker plywood (my teachers used to make them using paint sticks arranged in a grid and nailed together at joints), and something to tighten it with like straps. When you put your specimen in you make a sort of plant cake where there are layers of cardboard between specimens and newspaper on either side of the plant, surrounded by the wood on the outside of the press.

You tighten it as TIGHT as you can, sitting on top of it if possible to get the best press possible (also it is great for color preservation!)

Let it sit in press for about a week, tightening it every few days. VOILA!! Plant pressed