We recently worked with a library that needed to cable a room full of networked PCs and had a very limited budget. One of the items in the budget which came under scrutiny was cable trays. The solution was to substitute plastic rain gutters which are priced at less than 5 percent the cost of cable trays. The gutters were run along the wall and were also attached behind desks and tables. The trays were offset one inch from the table and desk edges so that cables could be run straight down between the work surface and the tray.