As an ex custom shop owner/operator,
I'd have to say: 1: Water Jet. or 2: Plasma Cutter - for quick efficient production runs.
Laser would be nice, but, I don't know of any shops w/ them or that would do small runs - and I'm in NY.
Using o/a torches is definitely another viable option, but, I'd say more for limited numbers..
Where water-jets produce the cleanest cuts..
Plasma will still require more clean-up from melting the metal
And Torch will create even more melted metal - needing to be cut off / ground / shaped / sanded..
Personally - I was more of a limited run custom shop, so, I'd use my plasma torch,
then manually use an angle grinder or Foredom rotary tool to grind/shape/sand
MILD Steel is pretty decent to work with..
Hot Rolled is the most 'user friendly'
Cold Rolled - is stronger and a bit more of a pain to work with.
AR [Abrasion Resistant] is super strong, and brutal to work with.
By *work with* - I mean using hand tools if/when needed
[due to the strength of the metals used]
1/4" isn't very thick - Until' it comes down to cutting / shaping / welding it.
Most 'consumer' tools aren't designed to work with metals that thick..
You could get away with using a drill, few bits, and a scroll-saw,
but by the time you get done with them, you'll have to shave again. lol
I still have a mini plasma cutter [250 amp TIG welder w/ plasma torch add-on]
It was okay for like 1/8" but would be a pain when doing upwards of 1/4"
Also, they require a pretty good compressor w/ high/steady CFM airflow
Sam -