Hello!
I want to make custom object as my teample i have Moneywell Computer and i want to make iMac G3
i found iMac G3 model here: Model
and i want to know how to correctly put that model into my package so display will work and other stuff in computer in the sims and i won't get any error in sim pe
Really thanks for any help.

You need a tutorial for making objects. If you haven't made objects before, I would suggest starting with one that doesn't need animated parts so you learn how to get the objects ingame and working first - it gets you through all the other hurdles (animated objects are more difficult, as all the objects have different skeletons to work with, and some also have morphs and various settings that can be confusing).

The ingame computers have animated parts, and it's not certain this particular mesh has its parts where those parts are, so whether anything can be animated or not depends on the mesh you've chosen.

Jinxsims has a 4t2 tutorial that covers basic object creation / replacing a mesh.
https://jinxxsims.tumblr.com/post/7...s-is-just-how-i
https://jinxxsims.tumblr.com/post/7...loo-step-twelve

https://jinxxsims.tumblr.com/post/7...-your-wonderful (one method to make GUIDs)

Joint assignment:
https://modthesims.info/t/433766
(I tend to use the "draw vertices with bone colors" tick box in an on/off way - it shows which vertices have been assigned to which bone. Can be useful if there are multiple joints and you're a bit unsure if everything has been assigned or where to, but it stops you from seeing what's marked, so that's why the on/off).

How they can be animated if all parts are as one model. When i exported model and opened it in blender everything was into one mesh and there was no skeleton doing objects with no animations is too easy like you just put model but... when i do model in blender and put in SimPE i get error about too much faces or something i forgot. So how i should correctly make object bc none of tutorials was updated to newest version of programs.
and this tutorial is for conversions i don't want to conver from 4 to 2 just make it from 0. and as i told all tutorials are for objects with no animations but i know that i can do this without animations it will be just wim putting disk into air but most mods with custom computers do that just i need to know how to export correctly and put in SimPE to corrctly possision screen

The meshes in TS2 have skeletons and are animated. The ones you get from sites like that usually don't.

If you export meshes as OBJ format from Blender directly to SimPE, you need to use these settings: https://i.postimg.cc/d0bRhWRH/Screenshot-New-159a.jpg
Otherwise you'll usually get some import errors and other problems.

The reason I posted a 4t2 tutorial is that it shows some Blender steps (exporting from Blender, and that adjusting the mesh size/shape/placement is often needed). It basically shows how to convert meshes and has most of the info you need to get an object from a file to ingame. If you have an OBJ mesh and a texture, you can use a 4t2 tutorial as a baseline (you just skip the parts about extracting the mesh in S4Studio).

The other tutorial shows how to link up a mesh to a skeleton. You can choose to not do this, but then you may find weird things happening with an item that's animated ingame - for a computer it would be the CD showing up from nowhere, or a mouse that doesn't work, and similar. If that's not a worry, but you still want the computer to have a working screen, you likely need to separate it from the computer and UVmap it to fit the screen map.

A computer isn't a good beginner project if you've never made anything for the game before. Just so you're aware.

With animation its quite normal for computer mods that sim enters cd nowhere and mouse isnt moving. But thanks

If you don't mind the computer not having animations, you can use the OBJ mesh. You likely will have to resize and reposition it, and possibly need to do some UVmapping (depending on how the textures are put together).

If you want the screen to work, you need to EITHER separate it from the computer and UVmap it to fit the screen map and then replace it separately with the screen mesh, OR fit the screen part from the original EA computer you clone with the screen in computer you want to replace it with. Otherwise the computer will not have a working screen.