sure you could make something from some drainage pipe its cheap stuff and they do screw on caps for it aswell you can get it cheaper but heres the idea its about 110mm in diameter
http://www.screwfix.com/p/single-soc...black-3m/49565
glue on the bottom end
http://www.screwfix.com/p/black-socket-plug-sp296/46863
screw on cap for other end
http://www.screwfix.com/p/black-scre...ap-sp292/22628