I used to build ss ones and cqr tombstones
both with viper v-foam, castle sab modules, horns I assume kenetic, hilclaire combined strobe and led. Finished with a bit of RS pluggable connector block so the lid could be removed.
I was 13 lol, the hard bit so you didn't get a bollocking was no bubbles or fingerprints on the stickers
the rest was piss easy.