I need to make this project, plase help me with some ideas
Do you mean you want to put your phone and a small SDR in a faraday cage together such that the SDR only receives the phone’s emissions? If so, a metal lunch box should work for everything except the power and data cables. Heavy RF choking of the cables just outside the box entry would take care of common mode current but you may face other RFI issues from the computer-to-SDR connection you’d have to solve. I hope this helps.
(Hopefully I won’t get downvotes for a best-guess answer to the question as currently stated.)