You can use blender & sollumz, become codex patreon on codewalker discord and get CodeX, you can also use 3ds max if you want… information is free, just ask around.
check also on modding support tutorials for Redm, here on forum [Tutorial] How to create custom MLO for RedM
by the way this is not Mlo among many others around here, this is Ymap.
Mlo have portals and objects on ytyp.
This is Ymap with some ydr. Mlo do not need anything to “not rain inside”
The best performance is to not use this lmao