base64clip.py

import base64
import pyperclip

target_file_path = r'C:\Users\user\Desktop\project.zip'

def chunks(lst, n):
    for i in range(0, len(lst), n):
        yield lst[i:i+n]

if __name__ == '__main__':
    with open(target_file_path, "rb") as f:
        b = f.read()
        b64 = base64.b64encode(b).decode('charmap')

        chunksize = 3145728
        b64_chunks = list(chunks(b64, chunksize))

        for idx, chunk in enumerate(b64_chunks):
            print("chunk", idx+1, "/", len(b64_chunks))
            pyperclip.copy(chunk)
            if len(b64_chunks) == idx+1:
                break
            input("Press Enter too continue...")

pip install pyperclip --user