A constructional toy comprising: a first element and a second element; the first element having a first engagement surface and a first engagement feature; the second element having a second engagement surface and a second engagement feature; wherein the engagement features (16,26) are configured such that the act of urging the engagement feature (16,26) of one element (10,12) into engagement with the engagement feature (16,26) of the other element (10,12) biases the engagement surfaces (14,24) into frictional engagement with one another; the first engagement feature comprises: a wall which defines a recess which extends beneath the first element engagement surface; and a first spline which extends from the recess wall part way, but not the whole way, across the recess; the first spline having an inner surface which faces into the recess and an outer surface which faces out of the recess; and the second engagement feature comprises: a second spline which extends above the second element engagement surface; the second spline having an inner surface which faces towards the second element engagement surface and an outer surface which faces away from the second element engagement surface; such that when the second spline is entered in the recess, and the inner surfaces (34,44) of the splines (32,42) are urged into engagement with one another, engagement surfaces (14,24) of the first element and second element are biased into frictional engagement with one another; characterised in that the first element engagement spline and second element engagement spline are configured to contact one another at a point (38, 48) along their respective inner surfaces (34,44). a first element and a second element; the first element having a first engagement surface and a first engagement feature; the second element having a second engagement surface and a second engagement feature; wherein the engagement features (16,26) are configured such that the act of urging the engagement feature (16,26) of one element (10,12) into engagement with the engagement feature (16,26) of the other element (10,12) biases the engagement surfaces (14,24) into frictional engagement with one another; the first engagement feature comprises: a wall which defines a recess which extends beneath the first element engagement surface; and a first spline which extends from the recess wall part way, but not the whole way, across the recess; the first spline having an inner surface which faces into the recess and an outer surface which faces out of the recess; and a wall which defines a recess which extends beneath the first element engagement surface; and a first spline which extends from the recess wall part way, but not the whole way, across the recess; the first spline having an inner surface which faces into the recess and an outer surface which faces out of the recess; and the second engagement feature comprises: a second spline which extends above the second element engagement surface; the second spline having an inner surface which faces towards the second element engagement surface and an outer surface which faces away from the second element engagement surface; a second spline which extends above the second element engagement surface; the second spline having an inner surface which faces towards the second element engagement surface and an outer surface which faces away from the second element engagement surface; such that when the second spline is entered in the recess, and the inner surfaces (34,44) of the splines (32,42) are urged into engagement with one another, engagement surfaces (14,24) of the first element and second element are biased into frictional engagement with one another; characterised in that the first element engagement spline and second element engagement spline are configured to contact one another at a point (38, 48) along their respective inner surfaces (34,44).