This is for stiffening the Y-Axis of your X-Carve. Per stiffener, you need:

• 2x m5 x 8 mm button hex screw (https://s.click.aliexpress.com/e/_d8YF8cV)
• 2x m5 t-nut (https://s.click.aliexpress.com/e/_dSRSU1X) OR drop-in t-nut (https://s.click.aliexpress.com/e/_dYOTSvB)

The different between the t-nut options is that the first ones require you to disassemble the rail to insert them. The second ones can be placed and removed freely (I used this ones, but the other ones are mechanically better).

I recommend from 2 to 3 stiffeners per side.

Also check https://www.thingiverse.com/thing:4219019 for the X axis