Contract Liability Insurance Versus Professional Liability Liability Insurance For A Small Cabinet Shop, Is There An Alternative?

Liability insurance for a small cabinet shop, is there an alternative? - contract liability insurance versus professional liability

We have 3 full time employees and 1 part time. They work with teams very dangerous. Could have a contract for the employees sign statements that assume the risk and responsibility of work-related accidents? Must be notarized. Would it make sense to rise to a claim for personal injury to our ownership of our employees to avoid too? We survived an insurance policy and would cost at around $ 6000.00 per year. We can not afford.
Thank you for your advice.
PS: We incorparated.