Q:

How can I fund my bank account with a credit card without paying interest?

Been trying to figure this out. I was thinking of setting up my own website selling a service and using paypal to accept credit card purchases,then using my credit card to "buy" the service off my own website, and then just transferring the money into my bank account from paypal. Of course I'll still have to pay a small fee... but nothing near the interest rate I would pay on a cash advance. 
Will it work? Is there an easier way? 

A:

Paypal and others will all charge ~2-3% for this, but this is against their ToS and the payment is likely to be reversed. If you're planning to avoid interest it means you intend to pay back this balance within ~30 days since carrying a balance on your credit card longer than that would result in interest.
So, if the annual interest rate on your credit card for cash advances is lower than 12x the percentage fee that you'd be charged by Paypal/other (if you even could) then you'd be better off taking the cash advance via credit card. This assumes no extra cash-advance fees.
There are cases where people use manufactured spending to satisfy credit card rewards requirements, commonly done by buying gift cards using the credit card and selling them for cash at a discount of ~10% (varies wildly). The only reason that makes sense to do is if the gap between qualifying for the reward and not is small. For example if you needed to spend $3000 in 3 months to earn $250 in rewards, only have $2500 in planned spending, so manufactured spending of $500 at $50 cost would make sense. It's a game that doesn't seem worth playing to me personally, but it can be done.
Ideally, you'd find an alternative that cost even less, and be working hard to save up an emergency fund to avoid the need for any of this, but I won't preach.

A:

Been trying to figure this out.

Why?
I'm sure most people on this board will disagree with me here, as generally the best advice for personal finance is to develop a strong allergy to debt.  It's, at least, good that you are avoiding a cash advance.
If you have the credit for it, you should really just get a personal loan.  The rates are better, the repayment terms are better, it's an all around better environment.  I have done this through credit card banks (Discover and American Express are good in this regard) and also through a peer to peer lender.
Barring the much better solution of a personal loan, depending on your specific credit card bank there are balance transfer checks.  Again, depending on your specific bank, you can write the balance transfer check to yourself in order to pay a vendor who may not accept credit card or third party checks.  You need to call your banks, and have honest up front discussions with them about what you intend to do.  
Working around the rules of your bank to concoct illegitimate transactions not only will contravene your agreement with the bank but likely anti-money-laundering laws.  Contriving a fake paypal invoice from a friend who cuts a check back to you will work but is, as far as I'm aware, illegal in the US apart from also breaching your agreement with the bank.
Start by researching a personal loan.  It's the best option.  Next look in to balance transfer options from various banks.  Don't self deal.

A:

Performing transactions which count as purchases on a credit card, while putting an equal (more or less) amount of money into a bank account is the fundamental activity in manufactured spend.  They do it to earn credit card sign-up bonuses, cashback, or mileage rewards, but you can use the same methods to perform an end-run around cash advance fees, or take advantage of promotional interest rates which apply only to purchases.
A couple of the tricks are:

Buy universal gift cards on credit and use them to load prepaid cards with a bill pay or ACH transfer feature.
Buy universal gift cards on credit and use them to buy money orders which can be deposited.
Use the credit card to overpay some account that issues refunds not restricted to the original method.

However, there are many details you need to be aware of, to avoid being caught up in anti-fraud measures, unexpected fees, or have your funds trapped in a near-useless form, so it's advised to do your research and then start small.  The fact that you had to ask the question, combined with the urgency it suggests, makes it probable that attempting this will not turn out well for you.
If you are a US taxpayer, there's one method available to you that is somewhat slow but sure with very predictable processing fees and a relatively large limit:

(Reddit) FAQ: Paying Federal Income Taxes with a credit card

Taxes fall into the third category above, "overpay some account that issues refunds not restricted to the original method".

