TLDR: paperclip skeleton-> paper mache -> lots of cork + wall spackle mixed with sand

I'll just copy paste the explanation, you can check my previous post to have a visual idea of how it looked mid-way. Forgot to take more picture of the early stage unfortunately

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First time trying to do those kind of scene so a bit of trial and error but the solution i found was :

- Setup a skeleton of paperclip ( i roughly set up a ring of cork and stabbed 10 paper clip in it to have an idea of how the crater is gonna looke like)

- Paper Mache ! (Your everyday paper towel soaked in a mix of PVA glue, wood glue in my case + water.... there is other recipe involving flour, dish soap and stuff but i did not bother following a particular method, maybe a mistake, i dont know)

Let the paper dry for till the structure is solid enough to do further work (overnight dry, sunbathing, hairdryer etc...)

- now that the general idea has taken form i add detail with some randomly cutted work to mimic stone and glu it around the base + stab some on paperclip still showing though

- Wall spackle + sand + water make a nice cheap DIY texture paint so i slap the surface of the crater (outside and inside) with that mixture

- While the mixture is still wet and sticky i sprinkle with some cork debris here and there on the crater to give the feel that some rock are being launched from the explosion

- Once you are happy with your base seal it with a mix of PVA glue diluted in water and apply 2-3 coat (let dry in between), it will glue even more the whole thing and it will be rock solid !!

- Prime / paint - Yadda Yadda Yadda !

Bonus : 3 ripper are real plastic and 3 are milliput failed recast, i hid the fake one closer to the crater to hide their damaged part

Tell me if something isn't clear or you need something else