I can't help with any modelling things, but the best place to put in a request for that sutff is in the
Models & Textures subforum we have at TF2M. Beyond that you could try contacting a modeller directly, TF2M chat has a couple and the TF2 Emporium would have a lot more.
I can give some feedback on your map after playing it though.
Considering your map is intended to be Normal difficulty, your waves are generally too hard. The first wave isn't too bad, we could handle that relatively well even with only four people, that's the kind of difficulty standard you should aim for across your whole popfile. Wave 2 rather quickly ramped up the difficulty, Giants, with Medics, with mini-crits, with Spies, with infinite cannon fodder is much too difficult at this stage. That said, it was by no means a bad wave and it could definitely work at a Normal difficulty level, so my suggestion is to move it - unchanged - to be either the last or second last wave.
Between waves 3 and 7 I honestly don't remember much, I think wave 3 was easier than wave 2 but none of the waves beyond wave 1 felt like Normal difficulty waves. Decoy is a great example of what Normal difficulty missions should entail - although your map is a bit bigger than Decoy, and should upscale to account for that - it sets a pretty good standard for all maps. A few things to note are that the first 2 waves only contain a relatively small number of robots split among a few basic types and nothing else. Wave 3 is just a tank and some Sniper/Spy support. Giants don't show up at all until wave 5. Only in the last 3 waves of Decoy do we start to see interesting combinations of robots emerge - more than half of the mission is used purely to isolate new threats and introduce them to the player, so they can be better prepared to deal with them later when things get a little crazier.
The last wave - while still feeling too difficult for a Normal mission - wasn't bad otherwise until the boss robot spawned. Personally, I think for a Normal difficulty mission a boss robot is out of the question. Continuing from what I said earlier - if Normal difficulty missions are best used to introduce the players to new types of threat, introducing an enemy that will only show up for that wave of that mission as a unique challenge doesn't fit at all. However, if you're determined to keep the boss robot as the final challenge of your map, then I have a few suggestions to bring him down to Normal difficulty. The first is to remove all other robots from the wave. Yes, all. Normal difficulty should be a cakewalk even for players who are only somewhat experienced with MvM, boss robots are generally titanic behemoths who cut bloody swathes through even the most die-hard MvM squads. Give them a chance and make the boss the sole enemy to beat. My other suggestion is to reduce his health by a significant amount. I don't know how much health he currently has, but his health should be around 30-40 thousand. Beyond that, I can't say much, as this wave will play drastically different without any other robots on the field, so further analysis would be required.
For
map feedback, I'll say this, it's damn pretty. You wouldn't expect a giant underground cavern to look so good, but that skybox works really well, I feel.
I said it during the test and I'll say it again, but the deathpit with the banana peel seems like it'd be entirely impossible to utilise in any situation. Bomb carriers don't walk past it at all and the doorway to it is so small that it'd be a lot of trouble to get a regular bot in there and impossible to get Giants in.
Lastly, there are a
lot of routes, it's true the map layout wasn't so confusing after running around in it for a while, but I like to think I have a good sense of direction and it was still a little daunting those first few waves.
A lot of good work here, looking forward to playing this again.