hook.Add("PlayerSpawnedProp", "HRP_PropOwnership", function (ply, mdl, ent)
    ent:SetNWString("owner", ply:SteamID64())
end)

hook.Add("PhysgunPickup", "HRP_PropBlock", function (ply, ent)
    if ent:IsPlayer() || ply:SteamID64() != ent:GetNWString("owner") then
        return false
    end

    return true
end)