Learn Farsi: شما باید خودتان این پروژه را طراحی کنید.

It means "yourselves" and is used here to intensify the subject شما (you). It emphasizes that you must do the designing, not someone else. It is formed by combining خود (self) with the plural "your" ending ـتان.

Could خودتان be placed right next to شما?

Yes, you could say شما خودتان باید... (You yourselves must...). When خود is used for emphasis, placing it directly after the pronoun it emphasizes is very common. However, placing it after the helping verb باید, as it is in this sentence, is also perfectly natural and keeps the same meaning.

Why does the verb طراحی کنید not have a می prefix?

The word باید (must) requires the action verb that follows it to be in the subjunctive mood. For the compound verb طراحی کردن (to design), you simply drop the continuous prefix می from می‌کنید to make the subjunctive form طراحی کنید.

What is the job of را here?

را is the specific direct object marker. The specific thing you are designing is این پروژه (this project). In Farsi, را must come immediately after the specific noun phrase it marks, showing that the project is receiving the action of being designed.