These are some things I use all the time for various uses. they are air line sleeves and self aligning fittings for compression fittings. they are available at most hardware stores and all NAPA parts stores. they are very cheap, only pennies each usually. I use them as velocity stacks, exhaust tips and the 1/8" brass fittings work great for axles in 1/24" scale as well as carb tops or short velocity stacks too. both of these are available in many sizes from 1/16" on up.
