3d mesh editor in web browser

i would like to create a software or use something to create a web browser functionality to modify meshes. I would like to have an fbx or obj as an input and output.
For example: i have a 3 predefined 3d meshes and i want to give the user to “play with them”.
User would be able to cut in one mesh and paste it into another mesh.
Could you please suggest what would be the best technology for doing this kind of project?

To simplify im showing the example in 2d squares
enter image description here

  1. Customer selects the 3rd mesh as a “base”
  2. Customer cuts something in 2nd mesh
  3. Customer drag and drop it on the “Base” mesh
    Step 2 and 3 can be done multiple times from multiple meshes.
  4. Customer can export the finished mesh as fbx or obj
  5. System should save information about:
    a) which mesh were used as a base
    b) from which mesh and what was taken to the final mesh

Thank you in advance!

in this moment i really don’t know how to approach the thing.
I was a developer so i think i will be able to learn everything to finish the work but i don’t know which technology would be the best.

This month i was helping my wife with some animations so i did an game in ureal so i was thinking that maybe i could do it as a “game” but setting up unreal for web browser is very resource heavy.

I checked some Js libraries (three.js and babylon.js) but to be honest there is so much “options” i would like to get an opinion from someone who have more experience in this area to suggest what could be a good fit.