If you use modelling ply you can cut it out with a knife, drill the holes by hand with sharp drill bits.
Cutting plastic cards up for control horns can almost be done with scissors. Cutting plastic sheet is easy, by half scoring then breaking, sand the edges smooth, job done.
Fire walls don’t actually have to be perfectly square, since as long as the motor is central the rest doesn’t matter that much, you can adjust the edges with a hand file if the first ones you cut are not perfectly squeezed are, as long as the power pod is square it’s not a problem.
Draw it onto the ply or stick the template on with spray tack again, then use a steel rule and knife to cut out the square. I do a strip of ply then cut the square firewalls off the strip. Pilot the holes with a small drill bit, I use a pinning vice and 1.3mm bit for that.
Again, if you use the pre cut kit you can learn all this stuff and get the tools over time as opposed to needing all of it AND the skills to get your plane airborne. With the speedbuild kit you only need to watch the video and have a single Stanley blade, straight edge and a hot glue gun to assemble it.