Source for thick inlay material?
 

I'm looking to make fret marker inlays that I will inlay into the edge of the fingerboard so that they will also serve as side markers. In order to have the proper visual impact as side markers, I think the inlay material needs to be thicker than the usual .050 thickness; maybe as thick as .1"

To complicate matters, I need blue paua, gold MOP, white MOP and red coral.

Any suggestions for a source?

Why do you think they need to be thicker? Std thickness worked fine for me for blue paua. Install them after the board is at final width.

If you remove too much thickness you could go be beyond the selected surface.

I think if they're only .050, they won't show up on the edge; especially after sanding flush.

You might want to reconsider your design idea.

Only a relatively thin layer of natural shell (known as the nacre layer) has the high level of iridescence that we look for. As you go beyond that layer the shell becomes a much plainer, duller calcium carbonate which doesn't have any of the qualities we look for in natural shell inlay.

The nacre layer is often thin enough that it disappears at the ends if you try to do a wide inlay on a radiused board. Inlay artists tediously sort to find premium thicker nacre layer on shell or do inlay using multiple sections that fit the curve better.

If you're worried about a final flush fit, intentionally install them low and level with clear CA glue. That's how Zipflex is installed.

As described by Rudy4, that "money" surface is only a mil or so thick.

You might consider reconstituted stone: http://rescuepearl.com/

It doesn’t have the problem of a nacre layer.

I use old piano key pads (ivory).

https://i.imgur.com/G0HMa3Z.jpg

https://i.imgur.com/8Ho5F1Y.jpg

I have cut quite a bit of inlay from actual shells. They can be bought from souvenir shops in resort areas. eBay is loaded with them.