Holders or Containers are objects other than buildings (House, Sewer) with fill and empty actions. All dens (Cave, Dog House, Graveyard) are buildings, stay in midground, and cannot be contained; portables/posables (Coffin, Urn) are not. But two buildings—one is oddly a vehicle—are below for they hold so much. Buildings usually hold 35 dots; some of them, House and Store, can't even fit a person! Each object has a room and a span. The former is listed below; the latter is more sketchy. Each holder has outside room and inside room.

Small

Middling

Great

1 sand, water, lava = 0 dots
1 marble (ball) = ·6? dots (This thing throws all metework above off. A marble standard would make everything roomier, if only for the marbles.)

1 sock = 1 dot/pixel/speck

1 pebble, shoe = 2 dots

1 worm, germ, amoeba = 3 dots

1 it, ball = 5 dots

1 key fob = 6 dots

1 rock = 7 dots

1 dog, win/starite = 9 dots

1 clock = 10 dots

1 baby = 11 dots

1 ghost, pole = 12 dots

1 metal door = 14 dots

1 man = 16·5 dots

1 blob, boulder = 20 dots

1 siren (creature) = 21 dots

1 cow = 24 dots

1 bike, large steel gate = 27 dots

1 ettin = 30 dots

1 wrecking ball = 35 dots

1 horse = 38 dots

1 bear = 44 dots

1 giraffe = 46 dots

1 motorbike = 48 dots

1 car = 51 dots

1 rhinoceros = 54 dots

1 hippopotamus = 58 dots

1 gyroglider/rotor kite = 61 dots

1 giant cog = 62 dots

1 huge boulder, ice block big = 64 dots

1 plane = 80·5 dots

1 ambulance = 92 dots

1 flying wing = 139 dots

1 UFO = 144 dots

1 tanker (vehicle) = 148 dots

1 battleship/dreadnought = 236 dots

1 ice block huge = 256 dots