I was just looking over the new MIDI Arpeggiator and it plays nicely and is lots of fun.
I had not used it on X1.

But I wanted to make try own patterns and the Help file says I can load and save Patterns,
but that menu item is no longer available.

See: http://www.cakewalk.com/Documentation/default.aspx?Doc=SONAR%20X2&Lang=EN&Req=Recording.13.19.html#1269253

I guess this is older data because the new arpeggiator uses ARP files.
Is there a way to create these files?



EDIT:

I see that I can change the file type filter for loading presets from ARP to PTN and load PTN files, but still, how do I make these myself?

take a look at the step sequencer?.. pretty straightforward to make and use patterns

I'm interested in this too. Creating and saving step sequencer patterns is easy enough, but how do I save these so that I can use them in the arpeggiator in X2? The step sequencer saves .ssp and the arpeggiator loads .ptn and .arp files. 
Additionally, it would be handy if I could just load midi-files into the arpeggiator. Sometimes things gets lost in translation in the conversion from midi to step sequencer pattern.
Any ideas on the matter would be great to hear.

I see that I can change the file type filter for loading presets from ARP to PTN and load PTN files, but still, how do I make these myself?

To the best of my knowledge, you need a copy of (the discontinued) Project 5 to create custom .ptn files. I know of no other method (beyond a squashed rumor about an in-house utility that Jesse Jost [ex-Cakewalk] developed). If memory serves, version 2.x had more options than version 1 or 1.5 with regards to .mid and .ptn conversions.
 

take a look at the step sequencer?.. pretty straightforward to make and use patterns

 P5 patterns (*.ptn) are not to be confused with Step Sequencer patterns (*.ssp).  Completely different animals.

Project5 - Free Stuff!
http://www.cakewalk.com/Support/kb/reader.aspx/20090612
 
 

Argh! I clicked thinking they'd released p5 as freeware...

If there was enough of a demand for it, I guess that I could dust off Project5 and reload all of the updates as an 'arp pattern editor'.  I'd heard reports of it still running as well as it ever did on a modern system.  It was always buggy if you pushed it.
 
Before I commit to that, check the boatload of included .ptns in ... \Cakewalk Content\SONAR X2 Producer\PTN MIDI Patterns\Arps\, or the 500 Alesion PTN Construction Kit / 500 Alesion ARP Presets from the link above.  No sense in reinventing the wheel here.
 
The latter two are based on a simple pattern length concept, but they cover a lot of ground.  Still. there are many arpeggiator directions that haven't been addressed in any form.  This particular arpeggiator is capable of just about any pattern that you can dream up.