What is the best way to make money with a pocket plane?

A hypothetical:

I now have in my possession a real, working pocket plane. Essentially it is a highly-configurable portal of variable size and shape that is attached to a plane of existence which apparently is all mine.

I want to make money off of this new toy.

Some caveats:

I can modify the portal - conceal it, attach it to existing objects, etc.

The portal is nigh-indestructible. That is to say, the nature of the material passing through it should not matter.

Revealing the existence of my pocket plane will obviously subject me to unwanted scrutiny and danger. I want to preserve my life while getting filthy, stinking rich.

My thought is transporting oil. Set up a deal with some oil cartel and transfer unlimited amounts of oil for the price of a single airplane ticket. Of course, my plane of existence will get a little messy, but I’ll figure that out later.

So… any thoughts? Kidnapping? Tours? Storage? Vault services?

Garbage disposal?

This is going to be potentially difficult because if you decide to go into business as a shipper or storage facility and expect to have little to no expenses, you may well face scrutiny unless you can conceal your accounting or totally cook your books. E.g. if you are transporting cargo containers all over the world for 90% of the old going rate but you are spending money only on international plane tickets, people will raise eyebrows. If you can keep your budget secret (don’t go IPO!), the IRS or other applicable taxation agency may raise an eyebrow as to how you are doing so well and investigate you for money laundering or something.

Can you operate your portal from the other side? Seems like there would be espionage/robbery possibilities if you could put yourself in your plane and mail yourself someplace, and then step out of the portal when no one was around. Although you’d have to have someone mail you, I guess.

And if would make the ultimate shoplifting device - put it in your pocket, and then drop various high value items in after - even if you’re searched, there is no evidence of your taking anything.

Joe

Set yourself up as a secure courier. Anything, anywhere, anytime. It would be all but impossible to intercept you except at the beginning and end of your trips.

Put the plane inside itself. Charge tickets to the end of the universe.

If you’ve got a flair for showmanship, you could become the world’s greatest stage magician.

Congratulations - you are now in possession of the world’s most secure maximum security prison system. Sell it to the highest bidder (because who wants thousands of dangerous criminals living in their pants?) and retire for life.

I think that a planar prison would be no different from a regular prison, logistics-wise, unless you’re willing to simply murder the inmates. However, you could avoid NIMBY concerns by having a portal have up a much smaller footprint.

Steal the sun. Hold the whole planet to ransom.

I’m a little unclear on the premise: are we talking about a limitless Bag of Holding, or a way of accessing an alternate universe? If the latter, what’s on the other side?