HOW DO I MAKE THIS A SOLID PART

I trying to make roys sword and i imorted roys supersmash bros sword model  but its suface and i need it to be a solid part please help https://cad.onshape.com/documents/8c822b9c67ed58148364dcf8/w/85c6fb47b0a4535e41cfee63/e/8a1b335b357c74f112a3299f

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