Dremel: Not much help. Too aggressive for almost everything.
A machinist ruler - made in usa. These are hardened and then tempered. They don’t bend and stay bent like the cheap chinese ones. They’re about 6 inches long, very often metric on one side, english on the other. I have a couple of these particular ones, and like them. https://www.amazon.com/PEC-Tools-flexible-Contrast-machinist/dp/B00ERY9GEQ/ref=sr_1_4?ie=UTF8&qid=1534706982&sr=8-4&keywords=machinist+ruler+6+inch
A deburring tool. I really like this one, it’s very durable, has a nice feel in the hand. Replaceable blades of many kinds (left hand, right hand, many special purposes…they’re all cheap) are available. I only use Noga blades - I’ve gotten a couple bad batches of chinese ones, and don’t bother with them any more.
A decent craft knife handle, and these blades. Not sure why, but the exacto brand have been “not as good as one would hope” recently. I have a fiskars handle that I like.
https://www.amazon.com/Excel-Blades-Replacement-Hobby-Blade/dp/B0006NAU9M/ref=sr_1_3?ie=UTF8&qid=1534707144&sr=8-3&keywords=excel+blades+%2311 and https://www.amazon.com/Excel-Blades-Replacement-Hobby-Blade/dp/B0006NAU9M/ref=sr_1_3?ie=UTF8&qid=1534707144&sr=8-3&keywords=excel+blades+%2311
A big battle with the nomad is material holding. For a lot of stuff, double stick carpet tape (see the wiki) works great - multi-layer acrylic sign material should be fine with tape. For others, you need something more substantial.
I strongly recommend the HTS threaded table. Expensive. Awesome. When you need it, you’ll know. http://www.hightechsystemsllc.com/pt_NomadPlateWithCams.html
Then, T-handled allen wrenches: like these: https://www.amazon.com/Eklind-51608-Standard-Cushion-T-Handle/dp/B0006HB1KK/ref=sr_1_2?ie=UTF8&qid=1534707797&sr=8-2&keywords=eklind+1%2F8 are really handy to have. I forget the size I use on the nomad, I think it’s 1/8".
For your “many signs” issue. The normal way to do that is with “tabs” that hold each sign solidly in the material while the others are cut, and the vast majority of the part gets cut with the cnc machine. Get it perfect, and you can just snap each part out of the material when you remove the whole thing from the table. Get it a little off, and a pair of small wire cutters snips each tab nicely. Touch up the snapped edge with a deburring tool by hand (takes a little practice) or a sanding block.
Optional stuff you should eventually get… but could wait.
A machinist square. These aren’t expensive. A combination square is not what you need. I like this type because the stop on the end of the short leg is REALLY handy. This gets used for aligning stuff on the table to the machine axis (by aligning it to the edge of the table, which is theoretically aligned already)
I also have one of these, which works well in the confines of the nomad’s cabinet
Calipers… I think if you’re doing any real work that needs any kind of accuracy, you need a pair, but you can live without them on a nomad. You shouldn’t, but you can. I “have an opinion” on this.
DECENT CALIPERS. Don’t cheap out on these. If you can’t afford a decent set of electronic calipers (real Mitutoyo, not cheap fakes, or off brand Chinese) get a set of mechanical calipers like these (B&S) https://www.ebay.com/p/Brown-Sharpe-599-579-5-Dial-Caliper-Stainless-Steel-Black-Face-0775zkv1/2254376512?iid=332768051875
If you’re paying less than $100 for a set of new Mitutoyo calipers, they’re fake. Here’s a used set: https://www.ebay.com/itm/Mitutoyo-500-196-20-150mm-6-Absolute-Digital-Digimatic-Vernier-Caliper/232885958241?epid=631355114&hash=item363915b661:g:Z4AAAOSwoiNbcOFd . If you’re paying $30 for something labeled Mitutoyo, they’re fake, even used, and you may as well be buying the cheap stuff then. Single biggest problem with cheap calipers is that the measurement will vary with battery state and temperature. Second biggest problem is that the battery will always be dead (their standby current is really high). The Fowler name is on lots of questionable stuff, don’t bother with that brand. I have a dozen pairs of calipers from various vendors (mechanical, electronic), and the Mitutoyo’s are the ones I always use. I have one pair of cheap electronic 12" calipers that I use in very special circumstances, always with a new battery.
As I said, I have a bit of an opinion there…