We do not currently have plans for a 2.85 mm or 3 mm filament version of Palette/Palette+. However, depending on what printer you have, there may be a quick fix.
We've seen that Ultimaker 2's can be changed to accept 1.75 mm filament with a few changes. Learn more here.
We offer a conversion kit for LulzBot printers. Learn more about this here.
If you have another brand of printer that only accepts 2.85 mm filament, you could share more about your printer and its intended uses at firstname.lastname@example.org, and we may be able to point you in the right direction.