You can purchase tunnels or make them out of paper towel or toilet paper rolls or empty oatmeal boxes with the bottom cut out. (smallanimalchanel.com)
(Lehmann kept her notes on cards that she stored in empty oatmeal boxes.) (discovermagazine.com)
This natural compound is a polysaccharide which provide the cholesterol lowering benefits of oats, the benefits oatmeal boxes constantly mention. (supernaturalacnetreatment.com)