finally met my friend who has a plastics making company to talk about my racket case and the results aren't that good.
Basically, there are two ways to make stuff from plastic -injection molding and thermoforming. In the first case, the plastic pallets are melted into liquid and injected with a help of special machinery into the mold. This is used for mass production and the mold costs start from ten thousand eur and goes waaayyy up. The more down to earth is thermoforming. Basically, you take a pre-made thin sheet of plastic, heat it to become soft and then it is pressed into form. This method is used for small batches, so the costs for a press-form start from a couple of hundred dollars up to a couple of thousands, but the premade plastic sheets are much more expensive than plastic pallets for injection molding.
For me to make a hard plastic case would cost ~200 dollars to make a form and ~10-30 for plastics depending on the plastic chosen. That would make the most expensive racket case ever
. Besides the costs, it seems that to make the case rigid enough (so that it couldn't be pressed in the middle without using a considerable amount of force) the plastic has to be really thick (at least 3 mm or so) and the sheets available aren't that aesthetically nice either..
It seems the plastic isn't the best material and I should explore other options, like making it from an aluminum sheet. So now the plan is during this/next week to see some metal fabricator and explore of its feasible.
Maybe someone has other ideas?