funny someone recently opened a thread in another section on "cutting the perfect body tube"
I'll show the pic of my homemake scrap alum tube cutting fixture and MOST important the internal mandrels used to get those perfect Factory cut edges your looking for, For most BT-5 to BT-50 tubes you can either get a hardwood dowel BT-5 having an internal size of .518" so .5" (1/2") hardwood dowels are perfect. Now but another 1/2" dowel they come 3 and 4 feet long if your using Totally tublars 34" tubes cut the dowel at 36" use the 1 foot scrap to beat into the clay nozzle end of 13 spent 18mm motors. twist and remove the dowel and all the clay, brunt debris ect for the casings. CA the casing onto your 36" dowel the using a 12" or longer sanding block and 120g paper sand down any ridges the may have appeared while assembling this mandrel. Apply CA to the entire outside surface and sand smooth. check the fit in one of your standard BR-20 tubes the mandrel should slide in easily but be firm inside the tube. Do the same with 24mm D motor casing. For larger sized tubes use larger dowels and build up with masking tape and or paper wraps. I have mandrels for just about every size from 1/8" launch lugs up to BT-101's that allow me to cut as little as 1/4" stop rings or as much as 18" from a 36" tube. so by adding or subtracting I can cut Any size tube 1/4" to 35-3/4" long with this very simple 19" long cutting jig.
The jig is made entirely of scrap aluminum angle and bar with 6 machine screws and 3 - thumbscrews. You can make something very similar with wood parts but be aware wood expands and contracts with moisture content in the air and may warp as well.
A combination of wood and plastics may also be a good alternative if your metal working skills are a little short. I can give you detailed parts list and instructions on construction this aluminum angle jig if you have a band or scroll saw, a hack saw, hand drill and a 10/24" tap and drill bit
PM me if you'd like to tackle the project. I believe I had the cutter fixture complete in an afternoon, using scrap junk I had laying around the house, that includes design and of coarse DOAH! time
As for cutting exhaust ports, there are two ways I use, first is a cheap old food store one hole paper punch. I found one for 1/8", 3/16" and 1/4" holes at verious art stores, food marts, and staples. Cheap!!!
The other way is to use those same mandrels we've been talking about inside to back up the tube while cutting square and rectangular and even very small round holes for pod and helicopter models with a very sharp #11 x-Acto knife.
Hope this helps.