Simple example usage script for MarchingCubes.cs at https://gist.github.com/cmdr2/b5326aa6fbf3c367747cc5ec31ba831e

MarchingCubesExample.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

// Simple example usage script for MarchingCubes.cs:
//  at: https://gist.github.com/cmdr2/b5326aa6fbf3c367747cc5ec31ba831e
//
// Attach to an empty GameObject in the scene
//
// Not optimized, performs poorly! Written for simple readability
//  and clarity, in order to get the most basic 'Marching Cubes'
//  implementation working in Unity.

[RequireComponent(typeof(MeshFilter))]
[RequireComponent(typeof(MeshRenderer))]
public class MarchingCubesExample : MonoBehaviour {
    MeshFilter mf;

    void Start() {
        mf = GetComponent<MeshFilter>();
        mf.sharedMesh = new Mesh();

        var grid = GetGrid(Vector3.zero, new Vector3(5, 5, 5), 0.1f);
        var tris = MarchingCubes.Polygonize(grid, 0);
        RenderTris(tris);
    }

    void RenderTris(List<MarchingCubes.Triangle> mcTris) {
        var verts = new List<Vector3>();
        var tris = new List<int>();
        var normals = new List<Vector3>();
        var uvs = new List<Vector2>();

        foreach (var tri in mcTris) {
            var n = tris.Count;

            verts.AddRange(tri.verts);
            tris.Add(n); tris.Add(n+2); tris.Add(n+1);

            var normal = Vector3.Cross(tri.verts[2] - tri.verts[0], tri.verts[1] - tri.verts[0]).normalized;
            normals.Add(normal); normals.Add(normal); normals.Add(normal);
        }

        mf.sharedMesh.SetVertices(verts);
        mf.sharedMesh.SetTriangles(tris.ToArray(), 0);
        mf.sharedMesh.SetNormals(normals);
    }

    MarchingCubes.GridCell[,,] GetGrid(Vector3 center, Vector3 gridSize, float cellSize) {
        var nGrid = gridSize / cellSize;

        var nX = Mathf.FloorToInt(nGrid.x);
        var nY = Mathf.FloorToInt(nGrid.y);
        var nZ = Mathf.FloorToInt(nGrid.z);

        var hX = nX * 0.5f;
        var hY = nY * 0.5f;
        var hZ = nZ * 0.5f;

        var grid = new MarchingCubes.GridCell[nX, nY, nZ];

        for (int i = 0; i < nX; i++) {
            var x = (-hX + i) * cellSize + center.x;

            for (int j = 0; j < nY; j++) {
                var y = (-hY + j) * cellSize + center.y;

                for (int k = 0; k < nZ; k++) {
                    var z = (-hZ + k) * cellSize + center.z;

                    var cell = new MarchingCubes.GridCell();
                    cell.verts[0] = new Vector3(x, y, z + cellSize);
                    cell.verts[1] = new Vector3(x + cellSize, y, z + cellSize);
                    cell.verts[2] = new Vector3(x + cellSize, y, z);
                    cell.verts[3] = new Vector3(x, y, z);
                    cell.verts[4] = new Vector3(x, y + cellSize, z + cellSize);
                    cell.verts[5] = new Vector3(x + cellSize, y + cellSize, z + cellSize);
                    cell.verts[6] = new Vector3(x + cellSize, y + cellSize, z);
                    cell.verts[7] = new Vector3(x, y + cellSize, z);

                    PopulateIsovalues(cell);

                    grid[i, j, k] = cell;
                }
            }
        }

        return grid;
    }

    void PopulateIsovalues(MarchingCubes.GridCell cell) {
        for (int i = 0; i < cell.verts.Length; i++) {
            cell.isovalue[i] = map(cell.verts[i]);
            //print(i + ", " + cell.isovalue[i]);
        }
    }

    float map(Vector3 pos) {
        return sdf_smin(
            sdf_sphere(pos, new Vector3(-0.7f, 0, 0), 1f),
            sdf_sphere(pos, new Vector3(0.7f, 0, 0), 1f),
            5
        );
    }

    float sdf_sphere(Vector3 pos, Vector3 center, float radius) {
        return Vector3.Distance(pos, center) - radius;
    }

    float sdf_smin(float a, float b, float k = 32) {
        float res = Mathf.Exp(-k*a) + Mathf.Exp(-k*b);
        return -Mathf.Log(Mathf.Max(0.0001f, res)) / k;
    }
}