I've been using what's called the tiered tape method that was introduced by Gold Coach Joe Slowinski. He wrote an article in Bowling This Month and has a video on it on YouTube, too.
He takes five pieces of tape to make the tier.
I've modified it a little bit and it makes it easier to put together.
I use one full piece of tape on the bottom. Then I cut the ends off of three pieces of full sized tape. Take one of the pieces left and cut in two equal halves. Take two of the remaining pieces and cut them to 3/4's length which will give you two 3/4 pieces and two 1/4 pieces. Place two 3/4 length pieces on the full size tape to start. Then place two of the 1/2 length pieces on top of that and then place the two 1/4 length pieces on top of that. I use one full sized piece of Real Bowler's Tape on top of that to cover the whole tiered tape unit.
I typically place the entire unit towards the bottom of the thumb hole on the front side of the hole. This unit fills in the gap of the tip end of your thumb so that you are not tempted to squeeze the ball during your swing. It sure helped me a lot as I used to squeeze the ball something terrible years ago.
Hope this helps... Try it. You'll like it. I hope...

I used to do that in my thumb. Kept it straight. Then, got the molded thumb.

Me2....Since going to a custom, molded thumb, I may or may not need 1 layer of the rough, white tape on the grip side (I like the feel but there isn't always room, depending on the girth of my thumb that day). Before, I was fiddling with tape ALL - THE - TIME. This is much simpler.

If you ever put in tape and find the fit just a little too tight, use a touch of Chapstick on the wide-sides and it will slip out easily. It also solves the problem of swelling if you suffer from that.

Ironically, everyone I know that has a custom thumb still uses tape. I guess if a person can afford 3 or 4 custom thumbs that might be best, but tape is quick and cheap.

Are you guys talking about the Exactacation technique?
Do you use the switchable thumbs stuff, too?
I talked to my PSO and he asked if I was having problems. My answer was no. His recommendation was to stay with what we've done thus far.
I've been reviewing my gear and have decided to get a few balls plugged and redrilled as a result of the new USBC rules.
I'm hoping I like my gear just like before and perhaps even better now.
With Boat convincing me that the dual angle method is the way to go (thanks Boat!), many of my newer balls are drilled with 50 deg. x 3 3/8" x 25 or 30 deg.
Some of the older balls used a bit different PAP measurement. So I'm getting caught up with the new measurements there, too.
Very happy with the Storm Code X ball and found the Son!Q to be working very nicely as well...

If you use a low or no flare ball to determine your PAP, it'll be correct regardless of what ball you use. I have an old Columbia Blue Dot that I used.

The EBI sensor puts my PAP precisely where, years ago, my driller decided it was by tracing oil rings...

Put a piece of white tape on your PAP and throw a few balls making a careful observation to see that the tape creates a solid white dot as the ball leaves your hand and for the first few feet. This will verify your PAP's accuracy. Next, pay close attention to how far the tape is tilted upward and how far it's rotated counter clockwise. This will give you some feeling for your axis tilt and axis rotation. Armed with this information, their are dozens of places that will make recommendations for drilling options based on these values.

the white tape is an old trick, Boat. And, it works.

So is drawing a horizontal line at the equator from oil ring to oil ring. Then dissecting it Vertically from oil ring to oil ring to find your PAP.

I found out to me using tape was more work and time than I wanted to get the fit right. Finally went to removable thumb. Use a tight fit then chapstick works for me