They look nice and are in neat rows, mounted five to a square bracket. Trouble is, I'm scared to try cutting them apart!

Use a micro razor saw.

http://umm-usa.com/onlinestore/product_info.php?products_id=35

Excellent tool.

The products from shapeway, though they can be outstanding, are very delicate and brittle. Don't use much pressure to remove from their "tree" or disaster awaits. Use saw or multiple very delicate swipes from a sharp hobby knife.

Or a very fine rotary saw mounted on a Dremel. Works every time.

That certainly looks like an excellent tool.
I'll need to get me one of those.
Thanks for the tip / Robin

This is the only way I remove parts from a sprue. I might use some nippers to get a sprue gate out of the way but then back to the micro saw. It is a must if you build Bronco and Miniart kit, IMHO. You can remove the small plastic parts without breaking.

I do like UMM-USA and use them for my needs but for the other sides of the pond CMK and RP tools have very similar products in case postage is out of reach.

I found that razor saw here in Europe after I noticed that Czech Republic was engraved/etched onto the saw blades:)
https://www.trolls.cz/collections/accessories/products/razor-saw-pack

/ Robin