How to make a girly room masculine?

So I am a trans guy who ****** himself over by picking the girlest decor ever. I have dark purple walls that I can't paint over, teal curtains and dark brown dressers. Also a small room. Idk how to make my room look manly without changing the wall color or furniture. I love DIY stuff, plus im not very rich so please keep that in mind
And so you can help better, I love minecraft, the color red, superwholock stuff, tumblr, and other things like that.
What are your suggestions?

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