lightweight bars, hollow or plastic inserted

[shelbycharger400]

i have seen pictures of them, where do you buy the hollow milled out bars or the ones with some sort of nylon in them to lighten up the bars?
anyone have a bar milled out?  i had one slot put in and a hole...its harder than u know what.
http://www.ehow.com/how_6866288_do-cut-firewood-living_.html

here is one that is milled out .

everything helps ,    i like usin my big saws most of the time, but they get heavy limbing up 4 to 6 inch and down.
YEP...project is a big cedar job and other small tree lines