Finally got a engineering format the way I like it

eng_format.py

from math import log10
def eng_str(x, significance=8, precision=3):
    y = abs(x)
    exponent = int(log10(y))
    engr_exponent = exponent - exponent%3
    z = y/10**engr_exponent
    if x < 0:
        z=z*-1
    if engr_exponent > 0:
        exp_str=f"+{engr_exponent:03}"
    else:
        exp_str=f"{engr_exponent:04}"
    return f"{z:{significance}.{precision}f}"+f"e{exp_str}"

print(eng_str(.00001))
print(eng_str(-.00001))
print(eng_str(123456.2342))
print(eng_str(-.1))

# Output
#  10.000e-006
# -10.000e-006
# 123.456e+003
#-100.000e-003