What everyday object compares to a cellplasma membrane?
An enclosed fence with doors. Though as with every analogy, it isn't perfect because the cellular membrane is fluid, its parts move about, whereas a fence's parts do not. A cell membrane is also not made up of only one material like homogenous fences are. Also, a cell membrane that has water inside and out self organises into a double layer, where both the inner and outer surface have a chemical affinity for water.