New to Shapeways, Multiple parts

Hi, I'm new so I'm sure I'm asking things already covered. I have modeled these parts
https://www.shapeways.com/model/937254/ssme.html?li=my-models &key=c875f3bb53dd939960056e3e4083ec30
and once I check how they print and that they can pass multiple prints with no issues, I plan on allowing them to be purchased. Since probably anyone who would buy them would need 3 copies of it, is it cheaper for me to make it a multiple part model? Also, if I decided to offer them as a set, would I need to sprue based on their size? And if I should sprue them, could the added volume of the sprue add more cost than the added cost of just leaving it one part and letting them order 3 separate?

Sorry, I know most of this has been covered probably, but I'm still poking around finding things.

Thanks,
Bill

It all depends on the material.

Indeed, it all depends on the material, but you may want a bit more details.

The cost of a Shapeways print is a fixed "handling charge" per item and a price that varies with the volume of material used.
(ceramics is different, but your piece doesn't look like it's designed for ceramics)

For most items, coupling three items together with a sprue should come rather cheaper that three single items, unless you make the sprue very massive. You save two handling charges, but spend extra for the sprue.

You can simply upload a number of variants and see for yourself. Shapeways calculates the price quite quickly after an upload.

Have a look at the materials data pages (under "Create" on the menu).

I hope this helps
Dragoman

Depending on the size of the objects and the material you may or may not need sprues - see here Sprues Yes or No.

Having said that, it is still not really clear to me what the rules are - it all seems a bit ad hoc.

If in doubt, you could email customer service, and ask them.

Yes, the "rules" for sprues are quite a bit ad-hoc at this time. We (designers) keep asking for things that they (producers) have trouble turning into repeatable items that are sellable.

You don't WANT a hard-fast rule at this time. Such a rule would likely be "no independent shells", and would shut down what many of us are attemping to design.

And if they were to establish a rule right now, it would very likely be more restrictive than what we would wish for.

The exchange for not having a rule is the flexibility to try impossible things. Sometimes, the production team will know that a design just can't work, or that it has trouble printing repetitively. Yes, it's frustrating having models rejected, but it's also (more) rewarding to try to pull off something that can't be built by traditional tools.

==

The biggest thing to keep in mind is that humans have to remove the items from the printer and place them in packages to ship. Tiny/fragile items are very likely to break.. believe me, I know. It's better to provide some protection as in this model than let them get broken, but I'd rather not have them arbitrarily rejected just because the forks on that forklift are so dainty.

If I was writing the "rule".. it'd be "items must at least be able to survive being handled between thumb and forefinger".. but that's not very scientific.