Hey I have a plastic dinosaur I wanna use a convert but its got air inside the body so is a soft squishy one what could I pour inside to fill it at a cheap cost?
Air dry clay or something similar. Cement is cheap, but might be a bit heavy and risks damaging the model when it sets.
Would some of those filler tubes builders use work? Some kind of expanding foam maybe. Just a guess, I've not tried it myself.
I'm thinking some expanding filler it has an air hole in it at the bottom but I'm looking to drill into it abit to build a howdah - gonna ask my mum if I can use the shed in the back as a hobby area and get into building more bits
Oh one more idea.... Spoiler This stuff is great, it comes in powder form, just add water and mix it in and pour in the dino, maybe slosh it around a bit to get in the points bits. and then just wait for it to dry... then it will be mostly indestructible.
Maybe something like this would work... It does well at expanding and should fill up the inside of your model nicely. Although not as strong as some of the other suggestions, it has the benefit of being very light. Bear in mind that I have never tried using this stuff for this purpose... just brainstorming.
Expanding foam is you're best bet but you should try it on a small part of the toy if its as soft as a child's play dino the foam could expand and completely change the shape of the toy...oh get yourself a ruber ducky you know the bath toy and filll it with the expanding foam and see if it warps the shape of that then. You know if it will happen to your toy
Expanding foam is to be handled with care imo... use little doses cause it really expands... depending on the product you use up to several times the volume... maybe @n810's suggestion is safer... something similar came to my mind... you know that stuff used to fill holes in the wall, if you're leaving a flat or your wife tells you to rearrange the interior design? Just mix it up with a lot of water, so it's really running liquid... might take some days to cure though, but it keeps the shape.. Here in Germany I'd get this Don't know what's it at your place, but just take a look diy ...
What about plaster of Paris? That should be fairly cheap and more durable than spackle or expanding foam if you are going to drill into it.