The case of OQO Model 01 is made of metal, it’s quite sturdy. However, the antenna covers are made of transparent plastic, which is prone to cracking.
In order to recover the cracked antenna covers I made a 3D model of the original antenna cover (antenna_cover.stl) and printed it on a photopolymer printer. I didn’t like the result, because the wall covering the antenna was too thin and fragile. So I decided to thicken the wall and sightly modified the original model. You can download the final model for 3D printing here: antenna_cover_fat.stl.