Objects always come out very expensive to make, using Blender

I am trying to design something that has 11 sides when looking at it from the y axis. It is basically a cylinder with only 11 sides on it's side. It's going to be 12 cm tall, 12 cm long and 6 cm wide.. Whether I design it to be solid or I try to design it hollow, the cost is over $300. I have uploaded other objects that other people have made that are less than $10 to produce.

I think I am not doing the extrude process correctly.

I start with an 11 sided cylinder, size it correctly and turn it on it's side.
In edit mode, I select one face on the end of the cylinder use "I" to inset faces enough to make a wall thickness.
I then select the inner face and select extrude to push the surface into the cylinder

When I upload this, the cost it about $100.

I add to this to make it fully enclosed by selecting the inner edges of the cylinder's "wall" on the open end and fill that space
Then I extrude it in some to form a solid wall over the cylinder's open end.
Then it costs more than $470.

Can anyone tell me what I am doing wrong or point me to some online tutorials for this?

Thanks

Price is based on volume. Your object is 131.5 cm3, so it's going to be expensive.

Yes that's correct. It's not related to Blender, it's the size of your model. Does it need to be so big? Does it need to be more than 4mm thick? See here for the materials costs: https://www.shapeways.com/materials/material-options

You seem to have created your model exactly as you want it, no problems there, it's just that 3d printing is not low-cost (not sure what these models are that cost under 10 usd - must be much smaller than yours).

This page should give some tips on designing cheaper objects.
https://www.shapeways.com/tutorials/design_for_cheaper_3d_pri nting

When you upload a file, you can see the volume of your model in cubic cm. You can use that info and some math to scale your model by the appropriate factor to reach your target price.

If you upload something that has a volume of 250 cm^3, then it will cost $1.50 + $1.40*250 = $351.50 in the white strong flexible plastic. If you want it to cost about $12 in the same material, then you have to scale the model by about 0.31 in each linear direction. The total cost would be $1.50 + $1.40*250*(0.31)^3 = $11.93.

An alternative to scaling down is to hollow it, but you have to be careful about minimal wall and wire thicknesses.

Also, if you hollow something out, you need to include an escape hole. If you upload a hollow model with no escape hole, Shapeways treats it as a solid object.