Solo 401k Loan or Individual 401k Loan 
Consider making solo 401k loan after you open solo 401k. Through a solo 401k loan, the self-employed business owner can gain access to low interest loan when compared to a traditional loan from a bank, especially if your credit is not to good, and you pay yourself back because the principal and interest payments flow back to the Solo 401k.
You Control Loan Terms
Also, since you are borrowing from your own solo 401k, you have more control over the loan terms. 
For example, while the loan period is generally  maximum of 5 years unless the funds are used towards the purchase of your primary residence, you can elect to make monthly or quarterly payments, no early prepayment penalties apply, the loan payments are fixed, and you have a quarterly payment grace period available. The loan interest rate is generally based on the current Wall Street prime rate plus one percent. 
Making, Processing Solo 401k or Individual 401k Loan
Under the solo 401k rules, the individual 401k loan must be in writing. Therefore, to document loan the solo 401k provider must provide you with following solo 401k loan docs. 
1. Loan Note/Agreement (must be executed by solo 401k trustee)
2. Payment Schedule