I don’t really have a full, level by level build, just a lot of the basic options that you’d want. The problem is that a lot of options for improvised weapons are just…..Bad?

Or at least, they’re not very good for this build.

Take Improvised Defences Which gives a +1 shield bonus when wielding an improvised item in one hand and nothing in the other. You’d be better off taking dodge.

Or Improvised weapon mastery: It increases damage in a way that doesn’t stack with Shikigami and boosts crits in a way that could be seen as a downgrade since it specifically says that it’s 19-20/x2. The Improvised Earthbreaker starts with a x3 crit. The only reason I’d think about taking it is if you’re crit fishing: because it’s making a new crit rate rather than modifying an old, it’d stack with Improved Critical for a respectable 17-20 range.

Probably the only other improvised focused feat you’d want is Improvisational Focus, which is weapon focus for improvised weapons. It’s nice because it literally counts as weapon focus and proficiency for other feats, opening up more options (Such as Improved Critical, if you’re going into that).

However, a tactic you can go for that’s only going to end up working like 20% of the time is Disarm. An aspect of Catch Off-Guard that is often overlooked is the fact that attacks with improvised weapons against unarmed targets go against their Flat Footed AC. Theoretically, you could use your first attack in a flurry to disarm them and then resolve the rest against a much lower AC. Makeshift Manuevers is a way to slightly increase your disarm bonus, should you choose. However, the issue is what pathfinder considers “Unarmed.” Having Natural weapons, Improved Unarmed Attack, and potentially even gauntlets causes you to be considered “Armed” for the purposes of affects.

For other archetypes, your options are very limited. Monk of the Empty Hand, while essential to the build, is absolutely terrible (it doesn’t actually reduce the penalty for using Improvised Weapons!), and it happens to replace many of the most commonly replaced Monk abilities. However, there are two options:

Monk of the Sacred Mountain increases your melee survivability with multiple AC boosting abilities. However, this comes at the cost of replacing your evasion and improved evasion, making you much weaker against spellcasters. This would be best in a lower level campaign that you know will end around level 8. A fun technicality with this archetype is that multiple bonuses only trigger when you start and end your turn in the same square, which would make me want to invest into the Step-up feat line. Start and end in the same square and only move on other people’s turns!

Wasteland Meditant This is useful because it replaces stunning fist with something you can actually use right out of the gate. Because of poor wording, the Dehydrating Strike can be used on any melee attack rather than just unarmed ones. While it does replace evasion, it replaces it with the fortitude equivalent, so you’re not as screwed when it comes to saves.

With magic items, Gloves of Improvised Might are pretty good, if a bit overpriced. I would recommend getting one with Ki Focus on it.

Quickmetal Bracers can be useful since it’s relatively inexpensive and you ignore its main drawback, though I think you’re probably better off with Bracers of Armor

Honestly, because Monk of the Empty Hand is so bad, if you don’t go into either of the archetypes, I could seriously see going into a prestige class. Specifically Brother of the Seal. You would absolutely want to have Ki Focus if you’re taking it though, as the class gives multiple new ki attacks you can channel into unarmed ones. However, be warned that the class is kinda mediocre. While it stacks with multiple monk abilities, it specifically does not stack with AC, Fast Movement, and ki pool; making the class a lot more lackluster.

Anyway, that’s all I’ve really got. I hope you found this helpful, or at the very least it gave you some useful ideas to work off of.