Hi, for smothing out printed hulls I've used regular red oxide (oil based) primer brushed on OK before though it's a bit thick for fine details -but he idea is that it should cover striations easily.
I can't vouch for sure, but my old Johnstones tin dried out after many years of service. I found a tin of "151 red oxide" and used it on my puffer and it worked great. 2 coats and makes sanding back inbetween
much easier -I use Revell enamel (email) as final coat(s).
Example: https://www.sealantsandtoolsdirect.co.uk/151-red-oxide-metal-topcoat-primer-paint-180ml-dy020aI don't have a good pic of before (only what I can see as the rough striations on my own pics.) but the couple of pics here of my puffer are of the worst curvature and I did not sand hard -just enough to key paint then sanded back after first coat and again after second. I also encclose a pic of the full hull. I think this was after 2 coats of primer with rough sanding, and maybe first or second coat of enamel. I used Zap maminating epoxy on other prints and it's much harder work to smooth back than using the red oxide primer and it seems to "float better and settle a smoother surface so far" -maybe epoxy is more resilient though I don't know...
Not sure if this helps, you can obviously substitute paints for what's available locally but I do always prefer oil based to acrylic.
Rich