A simple script for Unity where you can put in a list of prefabs to pull from randomly

RandomModelGenerator.cs

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

public class RandomModelGenerator : MonoBehaviour {

	public GameObject[] prefabs;
	public int seed;

	// Use this for initialization
	void Start () {
  //Initialize with a seed here if you want
  //Random.InitState (seed);
	}
	
	// Update is called once per frame
	void Update () {
		
	}

	public GameObject RandomModel() {

		if (prefabs.Length == 0){
			return null;
		}

		return prefabs[Random.Range (0, prefabs.Length)];

	}

}