Nancy go to a fabric store (We have JoAnns Fabrics) any large store should have this fabric called "PUL" . Doesn't need hemming. (it also can be wiped down you will see what I mean)used to make the outside of diapers covers in cute prints/boyish ones too.The one you need has a printed side this would be perfect! It comes wide 57 to 60inch . If you got it long so that it would go all the way from under the bed on one side to the other side and it tucked way under the bed just at your brothers hip and say wide as 36 inches + the width of bed+tucking under a good ways so it will stay!! P.S. at the store this fabric has other ones to go with it. One is a white wicking fabric to keep any wetness from the skin. So if you wanted this is how to make a Bed Pad: Layer #1 Printed "PUL" Print side down cut to size you want. #2 cut 1 or 2 flannel fabrics same size as PUL. Lay this on the unprinted side of the PUL. #3 Now the White Wicking fabric One Sides more SMOTHER that's NOT the side you want!! The OTHER Side IS! So cut this the same size as all others! hope this helps.  :)