The long spool type part should be okay to clamp in a vise, if the spool flanges are all the same diameter, and if the vise is long enough to contain the entire length of the part.
The bottom part looks very crushable, and a vise would not work directly on that. Instead, I would use 5C collets (if the diameter is below 1"). Now, I have a 4th axis which I'd likely use to hold it, with a 5C collet on the headstock end, and I'd allow for a sacrificial stub on the opposite end of the part during the machining. This stub would be about an inch or two long, and be captured in a second 5C collet in a 'tailstock' of sorts. Actually, what I have is a cheap 5C vertical/horizontal fixture I sometimes use for this purpose. I machined up a spacer block to hold the 5C fixture at the correct height to match my indexer.
Take note that my 5C tailstock idea is a 'dead and locked' support, and that the part cannot be indexed without releasing the collet, indexing and then reclamping. And the benefit of using this sort of tailstock support is the improved stiffness of the part during machining, versus using just a center hole, where end thrust is required to keep the part tight, and you'd likely find yourself crushing this part from end pressure.
Now if you are on a budget, you could make do with two matched vises, and two square 5C collet blocks, which you can often find sold in sets with a square and a hex 5C holder. You'd align the vises the desired distance apart, and put the collet blocks in, slide your workpiece through, clamp them down and machine.
First you get good, then you get fast. Then grouchiness sets in.
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)