For the time being a thick piece of foil with a rubber band or zip tie around it will suffice. DO NOT PUT A SHOP RAG IN THERE! Last thing you'll need is for the rag to dislodge and wrap around an accessory. You can order one or probably just find one from your local box store. If they don't have it in stock they can usually get it the next day.
2000 Mustang GT Steeda #0048 34k miles. 99 Cobra 4V swapped, FTBR IRS swapped, exhaust, tuned by James Gordon.
Just because I give you advice, doesn't mean I know more than you. Its just means I've done more stupid ****.