Set-up a custodial account with check writing privileges.

We have no part in inheritance but can buy it from the adults who do and i have custody of my little brother who is a beneficiary.

It usually comes in the form of a bank, security or custody statement."

On top of those you mentioned, there is also a chain of custody that you need to make sure they dump it on the correct landfill.

This is from Foremost: Business Personal Property CoverageInsurance protection against losses concerning the property of other people while it is in your care, custody and control.

For example, when divorcing couples separate, one will sometimes use the fact the other is cohabitating when it comes to arguing who should have custody of the children.

In order to establish a Solo 401k plan you need to have a legitimate self-employment activity that would produce 'earned' income, for example:Providing consulting services to clients and earning a fee as a result of thatReal estate agent helping a client buy or sell a property and earning a commissions as a result of thisBeing a "flipper": you buy a distressed property, fix it up an sell it for a profitetc. etc. etc.You don't 'earn' a rental income, it comes to you as a result of you making an investment, it is passive.Earned self-employment income is reported on a Schedule C of your tax return, where as rental income is reported on a Schedule E.If you have a 401k with the current employer most likely you will not be allowed to transfer it to another retirement account until one of the following occurs:You are no longer employed thereYou reach a retirement ageThere could be exceptions, but the chances are you can't move those funds.Your options would be either custodial self-directed IRA or if you wish to have a checkbook control you may want to explore IRA LLC option. 

Dan,you can't have a checking account for an IRA, this is custodian's role - have custody of your funds and IRA assets.

They are not able to custody assets and are not approved or overseen by the IRS or banking regulators.

Account Closed you can invest in the stock market but generally, only through a custodial account (parents on the account or manage it for you), that's what I did as a minor.