HIPS is one route but you can’t get a solvent, then how about PVA. PVA will dissolve in water.

Rob is talking high end F1 applications, so using pre-pregs. If your max Tg is 90 then you dont want to take it up to 160.

Acetone is commonly used for this 'lost core' sort of application, however immersing epoxy in acetone isn't really ideal. If it is the only way, then it probably wont suffer TOO much with only an hour, but I would want to make sure the epoxy is thoroughly cured - which realistically means giving it a post-cure up to your max Tg.

My epoxy specs sheet says : '' The maximum temperature resistance is at least 90 oC; however, some post curing is required in order to have service temperature of 60 - 70 oC.''
So i thought that the maximum temperature i can expose my part is 90C .Am i wrong on this ? When we say post curing what do we mean ? Is it safe for a cured part to be exposed at 140-160C?
Sorry  about  my inquiries but am totally new to the sport !

We never dissolve printed cores
Part is cooked 120/125
De bagged an de moulded
Then given a post cure at 140 or 160
At that temp the cores are like chewing gum
Thick gloves,grab the part straight out of the oven an flick the cores out with a scriber

I have a really hard time finding a D-Limolene supplier in Europe (D-Limolene is a solvent that dissolves HIPS plastic used as 3D printing material ) so my next best option is ABS . I want to print a mold core and after lamination to dissolve it , if i print in ABS i have to use acetone to dissolve it . I  must soak my core in acetone for an hour max , would this be enough to ruin my part ? I dipped a small part i made in acetone for couple of hours and i notice some small softening of the surface part but nothing major ,as far as i can see. Since i want my part to take loads i don't feel really comfortable using acetone . What is your view on this?