The MFJ-1899T Portable Multi Band Antenna is hard to keep in one place. It was designed for “walkabout” use. I tried propping it on chairs, taping it to the railing and even putting it into an empty box to keep it upright. If only I had a suction cup mount, I could place that portable antenna on any smooth surface.

Use an inexpensive dual suction cup Bath Safety Grip Handle sold by Harbor Freight (item#96086). This thing is meant to hold a person from slipping in the shower, and it is about the stickiest suction cup I have ever found.

Print using standard resolution and a 10% infill, 2 shells, and 0.20 mm layer height. These are standard print settings. I am pretty sure if you are ‘close enough’ the design will work for you too. It is a symmetrical part so you will need four pieces to make the mount shown. Each part piece took about 50 minutes to print on my printer. It is made out of PLA plastic filament material.
Assemble using Hillman part number 881526 14-20x2 Nylon machine screws, and Hillman 881556 ¼-20 Nylon wing nuts that you can obtain at any Lowes store. You will need 6 of each.

References:
[1] http://www.harborfreight.com/household/assisted-living/bath-safety-grip-handle-96086.html
[2] http://www.lowes.com/pd_139010-37672-881526_0__?Ntt=881526&UserSearch=881526&productId=3050761&rpp=32
[3] http://www.lowes.com/pd_138998-37672-881556_0__?Ntt=881556&UserSearch=881556&productId=3013046&rpp=32