What organelles are in an onion cell?
OK, so the first thing you always do when recreating a cell microscope slide (like drawing or modelling the cell) is that you only draw or model what you see. In your case, this would just be the nucleus, the cell membrane and the cell wall.

To answer your question, onion cells (you usually use epithelial cells for this experiment) are ‘normal’ cells with all of the ‘normal’ organelles: nucleus, cytoplasm, cell wall and membrane, mitochondria, ribosomes, rough and smooth endoplasmic reticulum, centrioles, Golgi body and vacuoles. You cannot see most of these as they appear translucent as well as being too small to see under the light microscope. You need an electron microscope to view these. Note: chloroplasts are not present in an onion cell as it is not a photosynthesising cell.

This is a typical onion cell slide with labels: