Summary

This is a model I came up with to help calibrate the Mendel Prusa I built. It has flat and curved surfaces, narrow columns, bridges over open space, and a means of determining build tolerances.

Instructions

I sliced this with Slic3R, with the following config settings:
acceleration = 0
bed_size = 200,200
bed_temperature = 60
bottom_layer_speed_ratio = 0.3
bridge_fan_speed = 100
bridge_flow_ratio = 1
bridge_speed = 25
cooling = 0
disable_fan_first_layers = 1
duplicate = 1
duplicate_distance = 6
duplicate_grid = 1,1
end_gcode = M104 S0 ; turn off temperature\nM140 S0; turn off hot bed\nG28 X0 ; home X axis\nM84 ; disable motors
extrusion_axis = E
extrusion_multiplier = 1
extrusion_width_ratio = 0
fan_always_on = 0
fan_below_layer_time = 60
filament_diameter = 1.75
fill_angle = 45
fill_density = 0.6
fill_pattern = rectilinear
first_layer_bed_temperature = 60
first_layer_height_ratio = 1
first_layer_temperature = 185
g0 = 0
gcode_arcs = 0
gcode_comments = 0
gcode_flavor = reprap
infill_acceleration = 50
infill_every_layers = 1
infill_speed = 40
layer_gcode =
layer_height = 0.2
max_fan_speed = 100
min_fan_speed = 35
min_print_speed = 10
notes =
nozzle_diameter = 0.35
output_filename_format = [input_filename_base].gcode
perimeter_acceleration = 25
perimeter_speed = 35
perimeters = 3
post_process =
print_center = 65,65
retract_before_travel = 2
retract_length = 1
retract_lift = 0
retract_restart_extra = 1
retract_speed = 30
rotate = 0
scale = 1
skirt_distance = 6
skirt_height = 1
skirts = 1
slowdown_below_layer_time = 15
small_perimeter_speed = 25
solid_fill_pattern = concentric
solid_infill_speed = 35
solid_layers = 3
start_gcode = G28 ; home all axes
support_material = 0
support_material_tool = 0
temperature = 185
travel_speed = 65
use_relative_e_distances = 0
z_offset = 0

Probably not optimum.

Printed in clear PLA, 1.75 mm. Probably not the best choice, since I work in a high humidity environment.

As designed there should be about 0.5 mm clearance between the ball and the cage, such that the ball is free inside the cage once the print is complete. My first print of this did not quite work out that way. it may need more clearance.
Also, this is my first project, and I am not too happy with the surface finishes I am getting. It would be nice to see what others can do with this.

Caged Ball