iMac for 3D Rendering

Check with FormZ at their web site and find out if their program is best optimized for one line of video cards. The iMacs come with some form of Radeon graphics card. At least mine did but it's a mid 2011. Double check to see what card is currently the top dog and whether FormZ will make full use of that card. You can't swap cards in an iMac so whether it's a good computer for you depends on how badly you have to squeek every bit of power out of the card and whether FormZ will use the iMac card well enough. 3D modeling and the drawing of polygons and such is, I think, the exact kind of thing that you may learn will work better with this or that card and you may want or need a particular video card. If the iMac card is fine, get the fastest SSD iMac you can get and add some fast Thunderbolt storage. 24gigs of ram or so and you're good to go.

There is only one high end video card available and that is available in the 27 inch screen iMac models.

The video card has 2 GBs of VRAM and is available as custom order option.

You will also need the higher end custom 3.4 Ghz i7 Intel CPU option, also.

Purchase either a dedicated SSD or the Fusion drive, if there is a budget issue.

Buy this configuration with the stock 8 GBs of RAM and plan to purchase more, less expensive RAM from either Online Mac memory websites Crucial memory or OWC(macsales.com). Their memory is completely Mac compatible, comes with lifetime guarantees, and is far cheaper than the price Apple charges for additonal memory.

Good Luck!