slist = {{0.5, 0.5, 0.5}};
While[
 Length[slist] < 7,
 a = RandomReal[1, 3];
 If[
  AllTrue[
   EuclideanDistance[a, #] & /@ slist,
   # > 0.4 &
   ],
  AppendTo[slist, a]
  ]
 ]