I bought long lengths of 1x 1- 1/2 untreated lumber and cut into 17 inch strips for top bars. I don't have a table saw, so I used Les Crowder's suggestion of quarter round molding strips as comb guides, which I cut to 13 1/2 " and glued and also tacked onto the bars with tiny nails. I'm happy with them, and my bees seem to be building on them quite nicely despite one side of the comb guide being flat and the other curved. All I own is a small battery operated circular saw and a drill, and built my own hive having no prior woodworking experience. I wouldn't say it was easy, but it was challenging and I learned so much I'm looking forward to making another one. If I can do it I'm sure you can!
Shanna Rose