Mcmaster Carr would be your source although nothing in those numbers, you will have to go 6061, 1/4 wall on the 5" and you can machine the OD to 1/8" wall and then go with the 4 1/2 x .250 wall and either bore the inside to .125 wall or machine the OD except where it goes into 5" (4.5 ID) and they do sell by the foot. other than that---I got nothing. When machineing a tube like that and so thin it will sing during the cut, I made a wood plug to fit the open end to support with a live center and use a brand new cutter/insert plus wd40 to get a nice finish