What should I do to my $20 pc?

Paid €20 for this pc. Wanna transform it into a mini sleeper pc.

Has an i5 2400, 16gb ram, gtx 745 and I added a brand new ssd in. Gonna probably get a gtx 1050ti, but my question remains:

What aestethics mods should I do? Should I paint it? (Which color?) Should I add a custom side window ? RGB ? Let me know!