I need someone who is skilled in Sculpting CAD Designing for 3-D printers.

I crafted in my garage, a rough prototype of a costume headpiece. I took the headpiece to a sculpture/CAD designer company who scanned the product and printed a miniature sample of the design on a small 3-D printer. After seeing the printed sample, I need to make modifications on it; then forward the .stl file to someone who has a large format 3-D printer (roughly 24" X 24" X 18") for printing a life-size sample. The current company is too large, slow, and expensive for me because they specialize in medical products. I need someone to simply make a few modifications to the existing .stl file of my product using my drawings and notes pointing out the changes. I need it done quickly.