Don't make such a thing with な

Grammar Explanation: The prohibitive な

During a competition, Touwata and Mizubashou confront Tsubaki’s group to ask for help. While Touwata lays out her request, Sazanka and Asagao tie the two with ropes, believing their plea to be a trick. Figuring they’ve won, Sazanka and Asagao let down their guard and fall into a trap.

ミズバショウ:: 「ゴメン、私(わたし)がさっき癖(くせ)で作(つく)っちゃったやつだ。」; “Sorry, I made that out of habit earlier.”
サザンカ:: 「癖(くせ)でこんなもん作(つく)るな！！」; “Don't make these things out of habit!”

Key Points

1作(つく)るな = “Don’t make it!”

Verb dictionary form + な is a blunt command telling someone not to do something.
Here, 作(つく)るな is an irritated scolding, not a polite request.

2こんなもん = こんなもの, with a dismissive spoken tone

もん is a casual spoken contraction of もの (“thing”).
こんなもん means “stuff like this” / “something like this”.
In an angry line like this, it sounds dismissive, more like “this kind of stuff” than a neutral “this item”.

3Dropped particle

Sazanka’s response drops を: こんなもん(を)作(つく)るな.