This thing has a couple of replacement dishwasher parts:
The slider piece has built-in support structures that you will need to snap/cut off after printing. I think it may be a fairly standard part, but you can adjust parameters in the openscad source if you want. Given that it bears 1/4 of the weight of the top rack, you should print with fairly high infill.
For the cutlery basket grids, either directly size the STLs to whatever size you need, or use the modules in the openscad source to make a custom grid.