立方体を等分割したメッシュを作成するEditor拡張。GPUパーティクル芸用なのでUV座標は入ってないし通常のシェーダではまともに表示されない可能性大。Editorフォルダに入れてメニューからCustom/Cube Mesh Makerを選択して使う。

CubeMeshMaker.cs

using UnityEngine;
using UnityEditor;

public class CubeMeshMakerWizard : ScriptableWizard
{
    public string filename = "mesh";

    public int xnum = 10;
    public int ynum = 10;
    public int znum = 10;

    [MenuItem("Custom/Cube Mesh Maker")]
    static void Init()
    {
        DisplayWizard<CubeMeshMakerWizard>("Cube Mesh Maker");
    }

    /// <summary>
    /// Createボタンが押された
    /// </summary>
    private void OnWizardCreate()
    {
        MeshMaker meshMaker = new MeshMaker();

        Mesh mesh = meshMaker.GenerageMesh(xnum, ynum, znum);
        
        AssetDatabase.CreateAsset(mesh, "Assets/" + filename + ".asset");
        AssetDatabase.SaveAssets();
    }
}

MeshMaker.cs

using System.Collections.Generic;
using UnityEngine;

public class MeshMaker {

    protected virtual bool IsInShape(Vector3 pos)
    {
        return true;
    }

    public Mesh GenerageMesh(int xnum, int ynum, int znum)
    {
        Mesh mesh = new Mesh();

        int vertexCount = xnum * ynum * znum;

        float xdiv = 1f / xnum;
        float ydiv = 1f / ynum;
        float zdiv = 1f / znum;

        List<Vector3> vertices = new List<Vector3>();
        List<int> indices = new List<int>();
        int index = 0;

        for (int i = 0; i < vertexCount; i++)
        {
            Vector3 pos = new Vector3((i % xnum) * xdiv, (i / xnum % ynum) * ydiv, (i / (xnum * ynum) % znum) * zdiv);

            if (IsInShape(pos))
            {
                vertices.Add(pos);
                indices.Add(index++);
            }
        }
        mesh.indexFormat = UnityEngine.Rendering.IndexFormat.UInt32;
        mesh.vertices = vertices.ToArray();
        mesh.SetIndices(indices.ToArray(), MeshTopology.Points, 0);
        mesh.RecalculateBounds();

        return mesh;
    }
}