Lay out a stretch of plasma membrane, a whole cell, a vesicle or a mitochondrion with its cristae. Each is a lipid bilayer drawn lipid by lipid along a smooth curve, heads on its two faces and tails meeting in the middle.
Drop an ion channel, a receptor, a transporter or a peripheral protein near a membrane and it snaps in, turned to the membrane, the lipids giving way. The electron-transport chain sets complexes I to IV, ubiquinone, cytochrome c and ATP synthase across the inner mitochondrial membrane, with the protons they pump.
Lay out a membrane, drop proteins near it and they snap in, then save the figure as SVG or PNG. The tool needs JavaScript, because the figure is drawn in your browser.