Give me suggestions to make my robot better off

VEX IQ General Discussion VEX IQ Robot Showcase
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IMG_20191017_1542243120×4160 1.58 MB
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IMG_20191017_1542133120×4160 1.7 MB
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IMG_20191017_1542183120×4160 1.71 MB
how can I add weight to the back of my robot or a different robot I can use to pick up blocks and balls