recreate and improve a 3d print idea

Description

I have designed a cover for a plug socket cover i want redesigned and improved.
i have the STL file, GLTF file and OBJ file (i designed it on tinkercad) but i want it imroved.
its important the dimensions of the back remain the same, and the holes are in the same position as it screws to the front of a plug socket, and the sides are angled in a simialar way so it pulls out once the wall has been plastered ok.
I would like some small additions made to it which would be amazing, however i would need to add this as a part which is 3d printed seperately. which would be a wago holder which goes on the back of the plate, to hold the wago connectors on the back of it.
I also want the recess on the top adjusted, so they stack on top of each other correctly (currently its a couple of mm out).
the dimensions for the wago connectors are Height: 8.3mm. Width: 18.7mm. Depth: 18.6mm (and ive attaced a image of the connector) along with a example of a wago holder to have something similar which can be glued on the back of the faceplace being designed
I also need another faceplate to be designed the same, for a double socket, but with the measurements at the bottom/back of 126mm wide x 68mm tall with the two screw holes located 120mm apart (centers) with a 4mm hole for the screw.
i can provide back drawings if need be (but it will be basic)
So i need
1 - My design improved (no writing) made stackable. 2 - My design amended to be the same design but in a double socket dimensions3 - a wago holder, big enough to hold 3 x 3 way wagos, and to be glued to the back of the faceplate.
these need to be provided in the original file for editing, and also a STL. they will be printed with a 0.4mm nozzle, in PLA or PETG.
please quote to complete the job, and also timescales.