What model are you looking to build? I have some experience that I can give you some input on too. As mentioned above, you can do the 2824-raffle for the older style five digits-DJ, but if you want to build a watch with a 3135 movement inside, I think it's best to buy a South-Korean case that is on eBay. The case fits the movement and dials directly. No modding is needed.
However, if you want to go with the affordable round, buying a raffle case and putting a 3135 movement inside, then I recommend you read the following posts:
3135-raffle info
custom movement ring for 3135-raffle case
The following links are sale posts by Pompomporin. Still, if you read the description section, you can see that the everyday things people did to the raffle cases are reshaping and modding the interior (inside) of the chance to take the 3135 dials. Also, if you look at the dial closely, not all are evenly spaced. However, it's much better than the stock case. The case back will be pushed against the rotor of the 3135. The though the watch will run, its rotor is not spinning, resulting in you wearing it but no power going into the movement as it should. Therefore, you must manually wind the watch every couple of days.
Raffle case shaped and movement fitting 1
Raffle Case shaped and movement fitting 2